mongod

Synopsis

mongod is the primary daemon process for the MongoDBsystem. It handles data requests, manages data access, and performsbackground management operations.

This document provides a complete overview of all command line optionsfor mongod. These command line options are primarily usefulfor testing: In common operation, use the configuration fileoptions to control the behavior ofyour database.

See also

Configuration File Settings and Command-Line Options Mapping

Note

Starting in version 4.0, MongoDB disables support for TLS 1.0encryption on systems where TLS 1.1+ is available. Formore details, see Disable TLS 1.0.

Options

• mongod

Starting in version 4.2

• MongoDB deprecates the SSL options and insteads adds newcorresponding TLS options.
• MongoDB adds—tlsClusterCAFile/net.tls.clusterCAFile. (Also availalbein 3.4.18+, 3.6.9+, 4.0.3+)

Core Options

• —help, -h
• Returns information on the options and use of mongod.

• —version
• Returns the mongod release number.

• —config <filename>, -f <filename>
• Specifies a configuration file for runtime configuration options. Theconfiguration file is the preferred method for runtime configuration ofmongod. The options are equivalent to the command-lineconfiguration options. See Configuration File Options formore information.

Ensure the configuration file uses ASCII encoding. The mongodinstance does not support configuration files with non-ASCII encoding,including UTF-8.

• —configExpand <none|rest|exec>
• Default: none

New in version 4.2.

Enables using Expansion Directivesin configuration files. Expansion directives allow you to setexternally sourced values for configuration file options.

—configExpand supports the following expansion directives:

ValueDescriptionnoneDefault. mongod does not expand expansion directives.mongod fails to start if any configuration file settingsuse expansion directives.restmongod expands rest expansion directives whenparsing the configuration file.execmongod expands exec expansion directives whenparsing the configuration file.

You can specify multiple expansion directives as a comma-separatedlist, e.g. rest, exec. If the configuration file containsexpansion directives not specified to —configExpand, the mongodreturns an error and terminates.

See Externally Sourced Configuration File Values for configuration filesfor more information on expansion directives.

• —verbose, -v
• Increases the amount of internal reporting returned on standard outputor in log files. Increase the verbosity with the -v form byincluding the option multiple times, (e.g. -vvvvv.)

Note

Starting in version 4.2, MongoDB includes the Debug verbosity level(1-5) in the log messages. For example,if the verbosity level is 2, MongoDB logs D2. In previousversions, MongoDB log messages only specified D for Debug level.

• —quiet
• Runs mongod in a quiet mode that attempts to limit the amountof output.

This option suppresses:

• output from database commands
• replication activity
• connection accepted events
• connection closed events

• —port <port>

• Default:

  • 27017 if mongod is not a shard member or a config server member
  • 27018 if mongod is a shard member
  • 27019 if mongod is a config server memberThe TCP port on which the MongoDB instance listens forclient connections.

• —bind_ip <hostnames|ipaddresses|Unix domain socket paths>
• Default: localhost

Note

Starting in MongoDB 3.6, mongod bind to localhostby default. See Default Bind to Localhost.

The hostnames and/or IP addresses and/or full Unix domain socketpaths on which mongod should listen for client connections. Youmay attach mongod to any interface. To bind to multipleaddresses, enter a list of comma-separated values.

Example

localhost,/tmp/mongod.sock

You can specify both IPv4 and IPv6 addresses, or hostnames thatresolve to an IPv4 or IPv6 address.

Example

localhost, 2001:0DB8:e132:ba26:0d5c:2774:e7f9:d513

Note

If specifying an IPv6 address or a hostname that resolves to anIPv6 address to —bind_ip, you must start mongod with—ipv6 to enable IPv6 support. Specifying an IPv6 addressto —bind_ip does not enable IPv6 support.

If specifying alink-local IPv6 address(fe80::/10), you must append thezone indexto that address (i.e. fe80::<address>%<adapter-name>).

Example

localhost,fe80::a00:27ff:fee0:1fcf%enp0s3

Tip

When possible, use a logical DNS hostname instead of an ip address,particularly when configuring replica set members or sharded clustermembers. The use of logical DNS hostnames avoids configurationchanges due to ip address changes.

Warning

Before binding to a non-localhost (e.g. publicly accessible)IP address, ensure you have secured your cluster from unauthorizedaccess. For a complete list of security recommendations, seeSecurity Checklist. At minimum, considerenabling authentication andhardening network infrastructure.

For more information about IP Binding, refer to theIP Binding documentation.

To bind to all IPv4 addresses, enter 0.0.0.0.

To bind to all IPv4 and IPv6 addresses, enter ::,0.0.0.0 orstarting in MongoDB 4.2, an asterisk "*" (enclose the asterisk inquotes to avoid filename pattern expansion). Alternatively, use thenet.bindIpAll setting.

Note

• —bind_ip and —bind_ip_all are mutually exclusive.Specifying both options causes mongod to throw an error andterminate.
• The command-line option —bind overrides the configurationfile setting net.bindIp.

• —bind_ip_all

New in version 3.6.

If specified, the mongod instance binds to all IPv4addresses (i.e. 0.0.0.0). If mongod starts with—ipv6, —bind_ip_all also binds to all IPv6 addresses(i.e. ::).

mongod only supports IPv6 if started with —ipv6. Specifying—bind_ip_all alone does not enable IPv6 support.

Warning

Before binding to a non-localhost (e.g. publicly accessible)IP address, ensure you have secured your cluster from unauthorizedaccess. For a complete list of security recommendations, seeSecurity Checklist. At minimum, considerenabling authentication andhardening network infrastructure.

For more information about IP Binding, refer to theIP Binding documentation.

Alternatively, you can set the —bind_ip option to ::,0.0.0.0or, starting in MongoDB 4.2, to an asterisk "*" (enclose theasterisk in quotes to avoid filename pattern expansion).

Note

—bind_ip and —bind_ip_all are mutually exclusive. Thatis, you can specify one or the other, but not both.

• —clusterIpSourceWhitelist <string>

New in version 3.6.

A list of IP addresses/CIDR (Classless Inter-Domain Routing) ranges against which themongod validates authentication requests from other members ofthe replica set and, if part of a sharded cluster, the mongosinstances. The mongod verifies that the originating IP iseither explicitly in the list or belongs to a CIDR range in the list. If theIP address is not present, the server does not authenticate themongod or mongos.

—clusterIpSourceWhitelist has no effect on a mongod started withoutauthentication.

—clusterIpSourceWhitelist accepts multiple comma-separated IPv4/6 addresses or ClasslessInter-Domain Routing (CIDR) ranges:

mongod --clusterIpSourceWhitelist 192.0.2.0/24,127.0.0.1,::1

Important

Ensure —clusterIpSourceWhitelist includes the IP address or CIDR ranges that include theIP address of each replica set member or mongos in thedeployment to ensure healthy communication between cluster components.

• —ipv6
• Enables IPv6 support. mongod disables IPv6 support by default.

Setting —ipv6 does not direct the mongod to listen on anylocal IPv6 addresses or interfaces. To configure the mongod tolisten on an IPv6 interface, you must either:

• Configure —bind_ip with one or more IPv6 addresses orhostnames that resolve to IPv6 addresses, or
• Set —bind_ip_all to true.

• —listenBacklog <number>
• Default: Target system SOMAXCONN constant

New in version 3.6.

The maximum number of connections that can exist in the listenqueue.

Warning

Consult your local system’s documentation to understand thelimitations and configuration requirements before using thisparameter.

Important

To prevent undefined behavior, specify a value for thisparameter between 1 and the local system SOMAXCONNconstant.

The default value for the listenBacklog parameter is set atcompile time to the target system SOMAXCONN constant.SOMAXCONN is the maximum valid value that is documented forthe backlog parameter to the listen system call.

Some systems may interpret SOMAXCONN symbolically, and othersnumerically. The actual listen backlog applied in practice maydiffer from any numeric interpretation of the SOMAXCONN constantor argument to —listenBacklog, and may also be constrained bysystem settings like net.core.somaxconn on Linux.

Passing a value for the listenBacklog parameter that exceeds theSOMAXCONN constant for the local system is, by the letter of thestandards, undefined behavior. Higher values may be silently integertruncated, may be ignored, may cause unexpected resourceconsumption, or have other adverse consequences.

On systems with workloads that exhibit connection spikes, for whichit is empirically known that the local system can honor highervalues for the backlog parameter than the SOMAXCONN constant,setting the listenBacklog parameter to a higher value may reduceoperation latency as observed by the client by reducing the numberof connections which are forced into a backoff state.

• —maxConns <number>
• The maximum number of simultaneous connections that mongod willaccept. This setting has no effect if it is higher than your operatingsystem’s configured maximum connection tracking threshold.

Do not assign too low of a value to this option, or you willencounter errors during normal application operation.

Note

Changed in version 2.6: MongoDB removed the upward limit on the maxIncomingConnectionssetting.

• —logpath <path>
• Sends all diagnostic logging information to a log file instead of tostandard output or to the host’s syslog system. MongoDB createsthe log file at the path you specify.

By default, MongoDB will move any existing log file rather than overwriteit. To instead append to the log file, set the —logappend option.

• —syslog
• Sends all logging output to the host’s syslog system ratherthan to standard output or to a log file (—logpath).

The —syslog option is not supported on Windows.

Warning

The syslog daemon generates timestamps when it logs a message, notwhen MongoDB issues the message. This can lead to misleading timestampsfor log entries, especially when the system is under heavy load. Werecommend using the —logpath option for production systems toensure accurate timestamps.

Starting in version 4.2, MongoDB includes the component in its log messages to syslog.

...  ACCESS   [repl writer worker 5] Unsupported modification to roles collection ...

• —syslogFacility <string>
• Default: user

Specifies the facility level used when logging messages to syslog.The value you specify must be supported by youroperating system’s implementation of syslog. To use this option, youmust enable the —syslog option.

• —logappend
• Appends new entries to the end of the existing log file when the mongodinstance restarts. Without this option, mongod will back up theexisting log and create a new file.

• —logRotate <string>
• Default: rename

New in version 3.0.0.

Determines the behavior for the logRotate command.Specify either rename or reopen:

• rename renames the log file.

• reopen closes and reopens the log file following the typicalLinux/Unix log rotate behavior. Use reopen when using theLinux/Unix logrotate utility to avoid log loss.

If you specify reopen, you must also use —logappend.

• —timeStampFormat <string>
• Default: iso8601-local

The time format for timestamps in log messages. Specify one of thefollowing values:

ValueDescriptionctimeDisplays timestamps as Wed Dec 3118:17:54.811.iso8601-utcDisplays timestamps in Coordinated Universal Time (UTC) in theISO-8601 format. For example, for New York at the start of theEpoch: 1970-01-01T00:00:00.000Ziso8601-localDisplays timestamps in local time in the ISO-8601format. For example, for New York at the start of the Epoch:1969-12-31T19:00:00.000-0500

• —traceExceptions
• For internal diagnostic use only.

• —pidfilepath <path>
• Specifies a file location to store the process ID (PID) of the mongodprocess . The user running the the mongod or mongosprocess must be able to write to this path. If the —pidfilepath option is notspecified, the process does not create a PID file. This option is generallyonly useful in combination with the the —fork option.

Linux

On Linux, PID file management is generally the responsibility ofyour distro’s init system: usually a service file in the /etc/init.ddirectory, or a systemd unit file registered with systemctl. Onlyuse the —pidfilepath option if you are not using one of these initsystems. For more information, please see the respectiveInstallation Guide for your operating system.

macOS

On macOS, PID file management is generally handled by brew. Only usethe —pidfilepath option if you are not using brew on your macOS system.For more information, please see the respectiveInstallation Guide for your operating system.

• —keyFile <file>
• Specifies the path to a key file that stores the shared secretthat MongoDB instances use to authenticate to each other in asharded cluster or replica set. —keyFile implies—auth. See Internal/Membership Authentication for moreinformation.

Starting in MongoDB 4.2, keyfiles for internal membershipauthentication use YAML format to allow formultiple keys in a keyfile. The YAML format accepts content of:

• a single key string (same as in earlier versions),
• multiple key strings (each string must be enclosed in quotes), or
• sequence of key strings.The YAML format is compatible with the existing single-keykeyfiles that use the text file format.

• —setParameter <options>
• Specifies one of the MongoDB parameters described inMongoDB Server Parameters. You can specify multiple setParameterfields.

• —nounixsocket
• Disables listening on the UNIX domain socket. —nounixsocket applies onlyto Unix-based systems.

The mongod processalways listens on the UNIX socket unless one of the following is true:

• —nounixsocket is set
• net.bindIp is not set
• net.bindIp does not specify localhost or its associated IP address

New in version 2.6: mongod installed from official .deb and .rpm packageshave the bind_ip configuration set to 127.0.0.1 bydefault.

• —unixSocketPrefix <path>
• Default: /tmp

The path for the UNIX socket. —unixSocketPrefix applies onlyto Unix-based systems.

If this option has no value, themongod process creates a socket with /tmp as a prefix. MongoDBcreates and listens on a UNIX socket unless one of the following is true:

• net.unixDomainSocket.enabled is false
• —nounixsocket is set
• net.bindIp is not set
• net.bindIp does not specify localhost or its associated IP address

• —filePermissions <path>
• Default: 0700

Sets the permission for the UNIX domain socket file.

—filePermissions applies only to Unix-based systems.

• —fork
• Enables a daemon mode that runs the mongod process in thebackground. By default mongod does not run as a daemon:typically you will run mongod as a daemon, either by using—fork or by using a controlling process that handles thedaemonization process (e.g. as with upstart and systemd).

The —fork option is not supported on Windows.

• —auth
• Enables authorization to control user’s access to database resourcesand operations. When authorization is enabled, MongoDB requires allclients to authenticate themselves first in order to determine theaccess for the client.

Configure users via the mongo shell. If no users exist, the localhost interfacewill continue to have access to the database until you createthe first user.

See Securityfor more information.

• —noauth
• Disables authentication. Currently the default. Exists for futurecompatibility and clarity.

• —transitionToAuth

New in version 3.4: Allows the mongod to accept and create authenticated andnon-authenticated connections to and from other mongodand mongos instances in the deployment. Used forperforming rolling transition of replica sets or sharded clustersfrom a no-auth configuration to internal authentication. Requires specifying a internalauthentication mechanism such as—keyFile.

For example, if using keyfiles forinternal authentication, the mongod createsan authenticated connection with any mongod or mongosin the deployment using a matching keyfile. If the security mechanisms donot match, the mongod utilizes a non-authenticated connection instead.

A mongod running with —transitionToAuth does not enforce user accesscontrols. Users may connect to your deployment without anyaccess control checks and perform read, write, and administrative operations.

Note

A mongod running with internal authentication and without—transitionToAuth requires clients to connectusing user access controls. Update clients toconnect to the mongod using the appropriate userprior to restarting mongod without —transitionToAuth.

• —cpu
• Forces the mongod process to report the percentage of CPU time inwrite lock, every four seconds.

• —sysinfo
• Returns diagnostic system information and then exits. Theinformation provides the page size, the number of physical pages,and the number of available physical pages.

• —noscripting
• Disables the scripting engine.

• —notablescan
• Forbids operations that require a collection scan. See notablescan for additional information.

• —shutdown
• The —shutdown option cleanly and safely terminates the mongodprocess. When invoking mongod with this option you must set the—dbpath option either directly or by way of theconfiguration file and the—config option.

The —shutdown option is available only on Linux systems.

For additional ways to shut down, see also Stop mongod Processes.

• —redactClientLogData

New in version 3.4: Available in MongoDB Enterprise only.

A mongod running with —redactClientLogData redacts any message accompanying a givenlog event before logging. This prevents the mongod from writingpotentially sensitive data stored on the database to the diagnostic log.Metadata such as error or operation codes, line numbers, and source filenames are still visible in the logs.

Use —redactClientLogData in conjunction withEncryption at Rest andTLS/SSL (Transport Encryption) to assist compliance withregulatory requirements.

For example, a MongoDB deployment might store Personally IdentifiableInformation (PII) in one or more collections. The mongod logs eventssuch as those related to CRUD operations, sharding metadata, etc. It ispossible that the mongod may expose PII as a part of these loggingoperations. A mongod running with —redactClientLogData removes any messageaccompanying these events before being output to the log, effectivelyremoving the PII.

Diagnostics on a mongod running with —redactClientLogData may be more difficultdue to the lack of data related to a log event. See theprocess logging manual page for anexample of the effect of —redactClientLogData on log output.

On a running mongod, use setParameter with theredactClientLogData parameter to configure this setting.

• —networkMessageCompressors <string>
• Default: snappy,zstd,zlib

New in version 3.4.

Specifies the default compressor(s) to use forcommunication between this mongod instance and:

• other members of the deployment if the instance is part of a replica set or a sharded cluster
• a mongo shell

• drivers that support the OP_COMPRESSED message format.MongoDB supports the following compressors:

• snappy

• zlib (Available starting in MongoDB 3.6)
• zstd (Available starting in MongoDB 4.2)In versions 3.6 and 4.0, mongod andmongos enable network compression by default withsnappy as the compressor.

Starting in version 4.2, mongod andmongos instances default to both snappy,zstd,zlibcompressors, in that order.

To disable network compression, set the value to disabled.

Important

Messages are compressed when both parties enable networkcompression. Otherwise, messages between the parties areuncompressed.

If you specify multiple compressors, then the order in which you listthe compressors matter as well as the communication initiator. Forexample, if a mongo shell specifies the following networkcompressors zlib,snappy and the mongod specifiessnappy,zlib, messages between mongo shell andmongod uses zlib.

If the parties do not share at least one common compressor, messagesbetween the parties are uncompressed. For example, if amongo shell specifies the network compressorzlib and mongod specifies snappy, messagesbetween mongo shell and mongod are not compressed.

• —timeZoneInfo <path>
• The full path from which to load the time zone database. If this optionis not provided, then MongoDB will use its built-in time zone database.

The configuration file included with Linux and macOS packages sets the timezone database path to /usr/share/zoneinfo by default.

The built-in time zone database is a copy of the Olson/IANA time zonedatabase. It is updated along with MongoDBreleases, but the release cycle of the time zone database differs from therelease cycle of MongoDB. A copy of the most recent release of the time zonedatabase can be downloaded fromhttps://downloads.mongodb.org/olson_tz_db/timezonedb-latest.zip.

wget https://downloads.mongodb.org/olson_tz_db/timezonedb-latest.zip
unzip timezonedb-latest.zip
mongod --timeZoneInfo timezonedb-2017b/

See also

processManagement.timeZoneInfo.

• —serviceExecutor <string>
• Default: synchronous

New in version 3.6.

Determines the threading and execution model mongod uses toexecute client requests. The —serviceExecutor option accepts oneof the following values:

ValueDescriptionsynchronousThe mongod uses synchronous networking and manages itsnetworking thread pool on a per connection basis. Previousversions of MongoDB managed threads in this way.adaptiveThe mongod uses the new experimental asynchronousnetworking mode with an adaptive thread pool which managesthreads on a per request basis. This mode should have moreconsistent performance and use less resources when there aremore inactive connections than database requests.

• —outputConfig

New in version 4.2.

Outputs the mongod instance’s configuration options, formattedin YAML, to stdout and exits the mongod instance. Forconfiguration options that uses Externally Sourced Configuration File Values,—outputConfig returns the resolved value for those options.

Warning

This may include any configured passwords or secrets previouslyobfuscated through the external source.

For usage examples, see:

• Output the Configuration File with Resolved Expansion Directive Values
• Convert Command-Line Options to YAML

Free Monitoring

New in version 4.0.

• —enableFreeMonitoring <runtime|on|off>

New in version 4.0: Available for MongoDB Community Edition.

Enables or disables free MongoDB Cloud monitoring. —enableFreeMonitoring accepts the followingvalues:

runtimeDefault. You can enable or disable free monitoring duringruntime.

To enable or disable free monitoring during runtime, seedb.enableFreeMonitoring() anddb.disableFreeMonitoring().

To enable or disable free monitoring during runtime whenrunning with access control, users must have requiredprivileges. See db.enableFreeMonitoring() anddb.disableFreeMonitoring() for details.onEnables free monitoring at startup; i.e. registers for freemonitoring. When enabled at startup, you cannot disable freemonitoring during runtime.offDisables free monitoring at startup, regardless of whetheryou have previously registered for free monitoring. When disabled at startup,you cannot enable free monitoring during runtime.

Once enabled, the free monitoring state remains enabled untilexplicitly disabled. That is, you do not need to re-enable each timeyou start the server.

For the corresponding configuration file setting, seecloud.monitoring.free.state.

• —freeMonitoringTag <string>

New in version 4.0: Available for MongoDB Community Edition.

Optional tag to describe environment context. The tag can be sent aspart of the free MongoDB Cloud monitoring registration at start up.

For the corresponding configuration file setting, seecloud.monitoring.free.tags.

LDAP Authentication or Authorization Options

• —ldapServers <host1>:<port>,<host2>:<port>,…,<hostN>:<port>

New in version 3.4: Available in MongoDB Enterprise only.

The LDAP server against which the mongod authenticates users ordetermines what actions a user is authorized to perform on a givendatabase. If the LDAP server specified has any replicated instances,you may specify the host and port of each replicated server in acomma-delimited list.

If your LDAP infrastructure partitions the LDAP directory over multiple LDAPservers, specify one LDAP server or any of its replicated instances to—ldapServers. MongoDB supports following LDAP referrals as defined in RFC 45114.1.10. Do not use —ldapServersfor listing every LDAP server in your infrastructure.

This setting can be configured on a running mongod usingsetParameter.

If unset, mongod cannot use LDAP authentication or authorization.

• —ldapQueryUser <string>

New in version 3.4: Available in MongoDB Enterprise only.

The identity with which mongod binds as, when connecting to orperforming queries on an LDAP server.

Only required if any of the following are true:

• Using LDAP authorization.
• Using an LDAP query for username transformation.
• The LDAP server disallows anonymous bindsYou must use —ldapQueryUser with —ldapQueryPassword.

If unset, mongod will not attempt to bind to the LDAP server.

This setting can be configured on a running mongod usingsetParameter.

Note

Windows MongoDB deployments can use —ldapBindWithOSDefaultsinstead of —ldapQueryUser and —ldapQueryPassword. You cannot specifyboth —ldapQueryUser and —ldapBindWithOSDefaults at the same time.

• —ldapQueryPassword <string>

New in version 3.4: Available in MongoDB Enterprise only.

The password used to bind to an LDAP server when using—ldapQueryUser. You must use —ldapQueryPassword with—ldapQueryUser.

If unset, mongod will not attempt to bind to the LDAP server.

This setting can be configured on a running mongod usingsetParameter.

Note

Windows MongoDB deployments can use —ldapBindWithOSDefaultsinstead of —ldapQueryPassword and —ldapQueryPassword. You cannot specifyboth —ldapQueryPassword and —ldapBindWithOSDefaults at the same time.

• —ldapBindWithOSDefaults <bool>
• Default: False

New in version 3.4: Available in MongoDB Enterprise for the Windows platform only.

Allows mongod to authenticate, or bind, using your Windows logincredentials when connecting to the LDAP server.

Only required if:

• Using LDAP authorization.
• Using an LDAP query for username transformation.
• The LDAP server disallows anonymous bindsUse —ldapBindWithOSDefaults to replace —ldapQueryUser and—ldapQueryPassword.

• —ldapBindMethod <string>
• Default: simple

New in version 3.4: Available in MongoDB Enterprise only.

The method mongod uses to authenticate to an LDAP server.Use with —ldapQueryUser and —ldapQueryPassword toconnect to the LDAP server.

—ldapBindMethod supports the following values:

• simple - mongod uses simple authentication.
• sasl - mongod uses SASL protocol for authenticationIf you specify sasl, you can configure the available SASL mechanismsusing —ldapBindSASLMechanisms. mongod defaults tousing DIGEST-MD5 mechanism.

• —ldapBindSASLMechanisms <string>
• Default: DIGEST-MD5

New in version 3.4: Available in MongoDB Enterprise only.

A comma-separated list of SASL mechanisms mongod canuse when authenticating to the LDAP server. The mongod and theLDAP server must agree on at least one mechanism. The mongoddynamically loads any SASL mechanism libraries installed on the hostmachine at runtime.

Install and configure the appropriate libraries for the selectedSASL mechanism(s) on both the mongod host and the remoteLDAP server host. Your operating system may include certain SASLlibraries by default. Defer to the documentation associated with eachSASL mechanism for guidance on installation and configuration.

If using the GSSAPI SASL mechanism for use withKerberos Authentication, verify the following for themongod host machine:

• Linux
• • The KRB5_CLIENT_KTNAME environmentvariable resolves to the name of the client Linux Keytab Filesfor the host machine. For more on Kerberos environmentvariables, please defer to theKerberos documentation.
  • The client keytab includes aUser Principal for the mongod to use whenconnecting to the LDAP server and execute LDAP queries.
• Windows
• If connecting to an Active Directory server, the WindowsKerberos configuration automatically generates aTicket-Granting-Ticket.aspx)when the user logs onto the system. Set —ldapBindWithOSDefaults totrue to allow mongod to use the generated credentials whenconnecting to the Active Directory server and execute queries.Set —ldapBindMethod to sasl to use this option.

Note

For a complete list of SASL mechanisms see theIANA listing.Defer to the documentation for your LDAP or Active Directoryservice for identifying the SASL mechanisms compatible with theservice.

MongoDB is not a source of SASL mechanism libraries, noris the MongoDB documentation a definitive source forinstalling or configuring any given SASL mechanism. Fordocumentation and support, defer to the SASL mechanismlibrary vendor or owner.

For more information on SASL, defer to the following resources:

• For Linux, please see the Cyrus SASL documentation.
• For Windows, please see the Windows SASL documentation.

• —ldapTransportSecurity <string>
• Default: tls

New in version 3.4: Available in MongoDB Enterprise only.

By default, mongod creates a TLS/SSL secured connection to the LDAPserver.

For Linux deployments, you must configure the appropriate TLS Options in/etc/openldap/ldap.conf file. Your operating system’s package managercreates this file as part of the MongoDB Enterprise installation, via thelibldap dependency. See the documentation for TLS Options in theldap.conf OpenLDAP documentationfor more complete instructions.

For Windows deployment, you must add the LDAP server CA certificates to theWindows certificate management tool. The exact name and functionality of thetool may vary depending on operating system version. Please see thedocumentation for your version of Windows for more information oncertificate management.

Set —ldapTransportSecurity to none to disable TLS/SSL between mongod and the LDAPserver.

Warning

Setting —ldapTransportSecurity to none transmits plaintext information and possiblycredentials between mongod and the LDAP server.

• —ldapTimeoutMS <long>
• Default: 10000

New in version 3.4: Available in MongoDB Enterprise only.

The amount of time in milliseconds mongod should wait for an LDAP serverto respond to a request.

Increasing the value of —ldapTimeoutMS may prevent connection failure between theMongoDB server and the LDAP server, if the source of the failure is aconnection timeout. Decreasing the value of —ldapTimeoutMS reduces the timeMongoDB waits for a response from the LDAP server.

This setting can be configured on a running mongod usingsetParameter.

• —ldapUserToDNMapping <string>

New in version 3.4: Available in MongoDB Enterprise only.

Maps the username provided to mongod for authentication to a LDAPDistinguished Name (DN). You may need to use —ldapUserToDNMapping to transform ausername into an LDAP DN in the following scenarios:

• Performing LDAP authentication with simple LDAP binding, where usersauthenticate to MongoDB with usernames that are not full LDAP DNs.
• Using an LDAP authorization query template that requires a DN.
• Transforming the usernames of clients authenticating to Mongo DB usingdifferent authentication mechanisms (e.g. x.509, kerberos) to a full LDAPDN for authorization.—ldapUserToDNMapping expects a quote-enclosed JSON-string representing an ordered arrayof documents. Each document contains a regular expression match andeither a substitution or ldapQuery template used for transforming theincoming username.

Each document in the array has the following form:

{
  match: "<regex>"
  substitution: "<LDAP DN>" | ldapQuery: "<LDAP Query>"
}

FieldDescriptionExamplematchAn ECMAScript-formatted regular expression (regex) to match against aprovided username. Each parenthesis-enclosed section represents aregex capture group used by substitution or ldapQuery."(.+)ENGINEERING""(.+)DBA"substitutionAn LDAP distinguished name (DN) formatting template that converts theauthentication name matched by the match regex into a LDAP DN.Each curly bracket-enclosed numeric value is replaced by thecorresponding regex capture group extractedfrom the authentication username via the match regex.

The result of the substitution must be an RFC4514 escaped string."cn={0},ou=engineering,dc=example,dc=com"ldapQueryA LDAP query formatting template that inserts the authenticationname matched by the match regex into an LDAP query URI encodedrespecting RFC4515 and RFC4516. Each curly bracket-enclosed numericvalue is replaced by the corresponding regex capture group extractedfrom the authentication username via the match expression.mongod executes the query against the LDAP server to retrievethe LDAP DN for the authenticated user. mongod requiresexactly one returned result for the transformation to besuccessful, or mongod skips this transformation."ou=engineering,dc=example,dc=com??one?(user={0})"

Note

An explanation of RFC4514,RFC4515,RFC4516, or LDAP queries is outof scope for the MongoDB Documentation. Please review the RFC directly oruse your preferred LDAP resource.

For each document in the array, you must use either substitution orldapQuery. You cannot specify both in the same document.

When performing authentication or authorization, mongod steps througheach document in the array in the given order, checking the authenticationusername against the match filter. If a match is found,mongod applies the transformation and uses the output forauthenticating the user. mongod does not check the remaining documentsin the array.

If the given document does not match the provided authentication name, orthe transformation described by the document fails, mongod continuesthrough the list of documents to find additional matches. If no matches arefound in any document, mongod returns an error.

Example

The following shows two transformation documents. The firstdocument matches against any string ending in @ENGINEERING, placinganything preceeding the suffix into a regex capture group. Thesecond document matches against any string ending in @DBA, placinganything preceeding the suffix into a regex capture group.

Important

You must pass the array to —ldapUserToDNMapping as a string.

"[
   {
      match: "(.+)@ENGINEERING.EXAMPLE.COM",
      substitution: "cn={0},ou=engineering,dc=example,dc=com"
   },
   {
      match: "(.+)@DBA.EXAMPLE.COM",
      ldapQuery: "ou=dba,dc=example,dc=com??one?(user={0})"
 
   }
 
]"

A user with username alice@ENGINEERING.EXAMPLE.COM matches the firstdocument. The regex capture group {0} corresponds to the stringalice. The resulting output is the DN"cn=alice,ou=engineering,dc=example,dc=com".

A user with username bob@DBA.EXAMPLE.COM matches the second document.The regex capture group {0} corresponds to the string bob. Theresulting output is the LDAP query"ou=dba,dc=example,dc=com??one?(user=bob)". mongod executes thisquery against the LDAP server, returning the result"cn=bob,ou=dba,dc=example,dc=com".

If —ldapUserToDNMapping is unset, mongod applies no transformations to the usernamewhen attempting to authenticate or authorize a user against the LDAP server.

This setting can be configured on a running mongod using thesetParameter database command.

• —ldapAuthzQueryTemplate <string>

New in version 3.4: Available in MongoDB Enterprise only.

A relative LDAP query URL formatted conforming to RFC4515 and RFC4516 that mongod executes to obtainthe LDAP groups to which the authenticated user belongs to. The query isrelative to the host or hosts specified in —ldapServers.

In the URL, you can use the following substituion tokens:

Substitution TokenDescription{USER}Substitutes the authenticated username, or thetransformedusername if a username mapping is specified.{PROVIDED_USER}Substitutes the supplied username, i.e. before eitherauthentication or LDAP transformation.

New in version 4.2.

When constructing the query URL, ensure that the order of LDAP parametersrespects RFC4516:

[ dn  [ ? [attributes] [ ? [scope] [ ? [filter] [ ? [Extensions] ] ] ] ] ]

If your query includes an attribute, mongod assumes that the queryretrieves a the DNs which this entity is member of.

If your query does not include an attribute, mongod assumesthe query retrieves all entities which the user is member of.

For each LDAP DN returned by the query, mongod assigns the authorizeduser a corresponding role on the admin database. If a role on the on theadmin database exactly matches the DN, mongod grants the user theroles and privileges assigned to that role. See thedb.createRole() method for more information on creating roles.

Example

This LDAP query returns any groups listed in the LDAP user object’smemberOf attribute.

"{USER}?memberOf?base"

Your LDAP configuration may not include the memberOf attribute as partof the user schema, may possess a different attribute for reporting groupmembership, or may not track group membership through attributes.Configure your query with respect to your own unique LDAP configuration.

If unset, mongod cannot authorize users using LDAP.

This setting can be configured on a running mongod using thesetParameter database command.

Note

An explanation of RFC4515,RFC4516 or LDAP queries is outof scope for the MongoDB Documentation. Please review the RFC directly oruse your preferred LDAP resource.

Storage Options

• —storageEngine string
• Default: wiredTiger

Note

Starting in version 4.2, MongoDB removes the deprecated MMAPv1 storageengine.

Specifies the storage engine for the mongod database. Availablevalues include:

ValueDescriptionwiredTigerTo specify the WiredTiger Storage Engine.inMemoryTo specify the In-Memory Storage Engine.

New in version 3.2: Available in MongoDB Enterprise only.

If you attempt to start a mongod with a—dbpath that contains data files produced by astorage engine other than the one specified by —storageEngine, mongodwill refuse to start.

• —dbpath <path>
• Default: /data/db on Linux and macOS, \data\db on Windows

The directory where the mongod instance stores its data.

If youinstalled MongoDB using a package management system, check the/etc/mongod.conf file provided by your packages to see thedirectory is specified.

Changed in version 3.0: The files in —dbpath must correspond to the storage enginespecified in —storageEngine. If the data files do notcorrespond to —storageEngine, mongod will refuse tostart.

• —directoryperdb
• Uses a separate directory to store data for each database. Thedirectories are under the —dbpath directory, and each subdirectoryname corresponds to the database name.

Changed in version 3.0: To change the —directoryperdb option for existing deployments, you mustrestart the mongod instances with the new —directoryperdbvalue and a new data directory (—dbpath <new path>), and thenrepopulate the data.

• For standalone instances, you can use mongodump onthe existing instance, stop the instance, restart with the new—directoryperdb value and a new data directory, and usemongorestore to populate the new data directory.
• For replica sets, you can update in a rolling manner by stoppinga secondary member, restart with the new —directoryperdb value anda new data directory, and use initial sync to populate the new data directory.To update all members, start with the secondary members first.Then step down the primary, and update the stepped-down member.

Not available for mongod instances that use thein-memory storage engine.

• —noIndexBuildRetry

Changed in version 4.0: —noIndexBuildRetry cannot be used inconjunction with —replSet; i.e., you cannotuse —noIndexBuildRetry for a mongod instance that is part ofa replica set.

Stops the mongod**standalone instance from rebuilding incomplete indexes on the nextstart up. This applies in cases where the mongod restarts after ithas shut down or stopped in the middle of an index build. In such cases,the mongod always removes any incomplete indexes, and then also, bydefault, attempts to rebuild them. To stop the mongod** fromrebuilding incomplete indexes on start up, include this option on thecommand-line.

The —noIndexBuildRetry only applies to standalones.

Not available for mongod instances that use thein-memory storage engine.

• —syncdelay <value>
• Default: 60

Controls how much time can pass before MongoDB flushes data to the datafiles via an fsync operation.

Do not set this value onproduction systems. In almost every situation, you should use thedefault setting.

Warning

If you set —syncdelay to 0, MongoDB will not sync thememory mapped files to disk.

The mongod process writes data very quickly to the journal andlazily to the data files. —syncdelay has no effect on thejournal files or journaling,but if —syncdelay is set to 0 the journal will eventually consumeall available disk space. If you set —syncdelay to 0 for testingpurposes, you should also set —nojournalto true.

The serverStatus command reports the background flushthread’s status via the backgroundFlushing field.

Not available for mongod instances that use thein-memory storage engine.

• —upgrade
• Upgrades the on-disk data format of the files specified by the—dbpath to the latest version, if needed.

This option only affects the operation of the mongod if the datafiles are in an old format.

In most cases you should not set this value, so you can exercise themost control over your upgrade process. See the MongoDB release notesfor more information about the upgrade process.

• —repair

Changed in version 4.0.3.

Runs a repair routine on all databases for a mongodinstance. The operation attempts to salvage corrupt data as well asrebuilds all the indexes. The operation discards any corrupt datathat cannot be salvaged.

Tip

If you are running with journaling enabled, there isalmost never any need to run repair since the server can use thejournal files to restore the data files to a clean state automatically.However, you may need to run repair in cases where you need to recoverfrom a disk-level data corruption.

Warning

• Only use mongod —repair if you have no other options.The operation removes and does not save any corrupt data duringthe repair process.
• Avoid running —repair againsta replica set member:
  • To repair a replica set member, if you have an intactcopy of your data available (e.g. a recent backup or an intactmember of the replica set), restore from that intactcopy instead(see Resync a Member of a Replica Set).
  • If you do choose to run mongod —repair against areplica set member and the operation modifies the data or themetadata, you must still perform a full resync in order for themember to rejoin the replica set.
• Before using —repair, make a backupcopy of the dbpath directory.
• If repair fails to complete for any reason, you must restart theinstance using the —repair option.

• —journal
• Enables the durability journal to ensure data files remain validand recoverable. This option applies only when you specify the—dbpath option. mongod enables journaling by default.

Not available for mongod instances that use thein-memory storage engine.

If any voting member of a replica set uses the in-memorystorage engine, you must setwriteConcernMajorityJournalDefault to false.

Starting in version 4.2 (and 4.0.13 and 3.6.14 ), if a replica setmember uses the in-memory storage engine(voting or non-voting) but the replica set haswriteConcernMajorityJournalDefault set to true, thereplica set member logs a startup warning.

• —nojournal
• Disables journaling. mongodenables journaling by default.

Not available for mongod instances that use thein-memory storage engine.

Starting in MongoDB 4.0, you cannot specify —nojournal option or storage.journal.enabled:false for replica set members that use theWiredTiger storage engine.

• —journalCommitInterval <value>
• Default: 100

The maximum amount of time in milliseconds thatthe mongod process allows betweenjournal operations. Values can range from 1 to 500 milliseconds. Lowervalues increase the durability of the journal, at the expense of diskperformance.

On WiredTiger, the default journal commit interval is 100milliseconds. Additionally, a write that includes or impliesj:true will cause an immediate sync of the journal. For detailsor additional conditions that affect the frequency of the sync, seeJournaling Process.

Not available for mongod instances that use thein-memory storage engine.

Note

Known Issue in 4.2.0: The —journalCommitInterval is missing in 4.2.0.

WiredTiger Options

• —wiredTigerCacheSizeGB <float>
• Defines the maximum size of the internal cache that WiredTiger willuse for all data. The memory consumed by an index build (seemaxIndexBuildMemoryUsageMegabytes) is separate from theWiredTiger cache memory. Starting in MongoDB 3.4, the values can rangefrom 0.25 GB to 10000 GB and can be a float.

Starting in MongoDB 3.4, the default WiredTiger internal cache size isthe larger of either:

• 50% of (RAM - 1 GB), or
• 256 MB.For example, on a system with a total of 4GB of RAM the WiredTigercache will use 1.5GB of RAM (0.5 (4 GB - 1 GB) = 1.5 GB).Conversely, a system with a total of 1.25 GB of RAM will allocate 256MB to the WiredTiger cache because that is more than half of thetotal RAM minus one gigabyte (0.5 (1.25 GB - 1 GB) = 128 MB < 256 MB).

Note

In some instances, such as when running in a container, the databasecan have memory constraints that are lower than the total systemmemory. In such instances, this memory limit, rather than the totalsystem memory, is used as the maximum RAM available.

To see the memory limit, see hostInfo.system.memLimitMB.

Avoid increasing the WiredTiger internal cache size above itsdefault value.

With WiredTiger, MongoDB utilizes both the WiredTiger internal cacheand the filesystem cache.

Via the filesystem cache, MongoDB automatically uses all free memorythat is not used by the WiredTiger cache or by other processes.

Note

The —wiredTigerCacheSizeGB limits the size of the WiredTiger internalcache. The operating system will use the available free memoryfor filesystem cache, which allows the compressed MongoDB datafiles to stay in memory. In addition, the operating system willuse any free RAM to buffer file system blocks and file systemcache.

To accommodate the additional consumers of RAM, you may have todecrease WiredTiger internal cache size.

The default WiredTiger internal cache size value assumes that there is asingle mongod instance per machine. If a single machinecontains multiple MongoDB instances, then you should decrease the setting toaccommodate the other mongodinstances.

If you run mongod in a container (e.g. lxc,cgroups, Docker, etc.) that does not have access to all of theRAM available in a system, you must set —wiredTigerCacheSizeGB to a valueless than the amount of RAM available in the container. The exactamount depends on the other processes running in the container. SeememLimitMB.

• —wiredTigerMaxCacheOverflowFileSizeGB <float>
• Specifies the maximum size (in GB) for the “lookaside (or cacheoverflow) table” file WiredTigerLAS.wt.

The setting can accept the following values:

ValueDescription0The default value. If set to 0, the file size isunbounded.number >= 0.1The maximum size (in GB). If the WiredTigerLAS.wtfile exceeds this size, mongod exits with afatal assertion. You can clear the WiredTigerLAS.wtfile and restart mongod.

To change the maximum size during runtime, use thewiredTigerMaxCacheOverflowSizeGB parameter.

Available starting in MongoDB 4.2.1 (and 4.0.12)

• —wiredTigerJournalCompressor <compressor>
• Default: snappy

New in version 3.0.0.

Specifies the type of compression to use to compress WiredTigerjournal data.

Available compressors are:

• none
• snappy
• zlib
• zstd (Available starting in MongoDB 4.2)

• —wiredTigerDirectoryForIndexes

New in version 3.0.0.

When you start mongod with —wiredTigerDirectoryForIndexes, mongod stores indexes and collections in separatesubdirectories under the data (i.e. —dbpath) directory.Specifically, mongod stores the indexes in a subdirectory namedindex and the collection data in a subdirectory namedcollection.

By using a symbolic link, you can specify a different location forthe indexes. Specifically, when mongod instance is notrunning, move the index subdirectory to the destination andcreate a symbolic link named index under the data directory tothe new destination.

• —wiredTigerCollectionBlockCompressor <compressor>
• Default: snappy

New in version 3.0.0.

Specifies the default compression for collection data. You canoverride this on a per-collection basis when creating collections.

Available compressors are:

• none
• snappy
• zlib
• zstd (Available starting MongoDB 4.2)—wiredTigerCollectionBlockCompressor affects all collections created. If you changethe value of —wiredTigerCollectionBlockCompressor on an existing MongoDB deployment, all newcollections will use the specified compressor. Existing collectionswill continue to use the compressor specified when they werecreated, or the default compressor at that time.

• —wiredTigerIndexPrefixCompression <boolean>
• Default: true

New in version 3.0.0.

Enables or disables prefix compression for index data.

Specify true for —wiredTigerIndexPrefixCompression to enable prefix compression forindex data, or false to disable prefix compression for index data.

The —wiredTigerIndexPrefixCompression setting affects all indexes created. If you changethe value of —wiredTigerIndexPrefixCompression on an existing MongoDB deployment, all newindexes will use prefix compression. Existing indexesare not affected.

Replication Options

• —replSet <setname>
• Configures replication. Specify a replica set name as an argument tothis set. All hosts in the replica set must have the same set name.

Starting in MongoDB 4.0,

• —replSet cannot be used in conjunction with—noIndexBuildRetry.
• For the WiredTiger storage engine, —replSet cannot be used inconjunction with —nojournal.If your application connects to more than one replica set, each setshould have a distinct name. Some drivers group replica setconnections by replica set name.

• —oplogSize <value>
• Specifies a maximum size in megabytes for the replication operation log(i.e., the oplog).

Note

Starting in MongoDB 4.0, the oplog can grow past its configured sizelimit to avoid deleting the majority commit point.

By default, the mongod process creates an oplog based onthe maximum amount of space available. For 64-bit systems, the oplogis typically 5% of available disk space.

Once the mongod has created the oplog for the first time,changing the —oplogSize option will not affect the size of the oplog.

To change the oplog size of a running replica set member, use thereplSetResizeOplog administrative command.replSetResizeOplog enables you to resize the oplogdynamically without restarting the mongod process.

See Oplog Size for more information.

• —enableMajorityReadConcern
• Default: True

Starting in MongoDB 3.6, MongoDB enables support for"majority" read concern by default.

You can disable read concern "majority" to preventthe storage cache pressure from immobilizing a deployment with athree-member primary-secondary-arbiter (PSA) architecture. For moreinformation about disabling read concern "majority",see Disable Read Concern Majority.

To disable, set —enableMajorityReadConcern to false. —enableMajorityReadConcern has no effect forMongoDB versions: 4.0.0, 4.0.1, 4.0.2, 3.6.0.

Important

In general, avoid disabling "majority" read concernunless necessary. However, if you have a three-member replica setwith a primary-secondary-arbiter (PSA) architecture or a shardedcluster with a three-member PSA shards, disable to prevent thestorage cache pressure from immobilizing the deployment.

Disabling "majority" read concern affects support fortransactions on sharded clusters. Specifically:

• A transaction cannot use read concern "snapshot" ifthe transaction involves a shard that has disabled readconcern “majority”.
• A transaction that writes to multiple shards errors if any of thetransaction’s read or write operations involves a shard that hasdisabled read concern "majority".However, it does not affect transactionson replica sets. For transactions on replica sets, you can specifyread concern "majority" (or "snapshot"or "local" ) for multi-document transactions even ifread concern "majority" is disabled.

Disabling "majority" read concern disables supportfor Change Streams for MongoDB 4.0 and earlier. For MongoDB4.2+, disabling read concern "majority" has no effect on changestreams availability.

Sharded Cluster Options

• —configsvr
• Required if starting a config server.

Declares that this mongod instance serves as the configserver of a sharded cluster. Whenrunning with this option, clients (i.e. other cluster components)cannot write data to any database other than configand admin. The default port for a mongod with this option is27019 and the default —dbpath directory is/data/configdb, unless specified.

Important

Starting in 3.4, you must deploy config servers as a replica set.The use of the deprecated mirrored mongod instances asconfig servers (SCCC) is no longer supported.

The replica set config servers (CSRS) must run theWiredTiger storage engine.

The —configsvr option creates a local oplog.

Do not use the —configsvr option with —shardsvr. Configservers cannot be a shard server.

Do not use the —configsvr with theskipShardingConfigurationChecks parameter. That is, ifyou are temporarily starting the mongod as astandalone for maintenance operations, include the parameterskipShardingConfigurationChecks and exclude —configsvr.Once maintenance has completed, remove theskipShardingConfigurationChecks parameter and restartwith —configsvr.

• —configsvrMode <string>
• Available in MongoDB 3.2 version only

If set to sccc, indicates that the config servers are deployedas three mirrored mongod instances, even if one or moreconfig servers is also a member of a replica set. configsvrModeonly accepts the value sccc.

If unset, config servers running as replica sets expect to use the“config server replica set” protocol for writing to config servers,rather than the “mirrored mongod” write protocol.

• —shardsvr
• Required if starting a shard server.

Configures this mongod instance as a shard in asharded cluster. The default port for these instances is27018.

Important

Starting in MongoDB 3.6, you must deploy shards as replica sets. See the —replSetoption to deploy mongod as part of a replica set.

Do not use the —shardsvr with theskipShardingConfigurationChecks parameter. That is, ifyou are temporarily starting the mongod as astandalone for maintenance operations, include the parameterskipShardingConfigurationChecks and exclude —shardsvr.Once maintenance has completed, remove theskipShardingConfigurationChecks parameter and restartwith —shardsvr.

• —moveParanoia
• If specified, during chunk migration, a shard saves,to the moveChunk directory of the —dbpath, all documentsmigrated from that shard.

MongoDB does not automatically delete the data saved in themoveChunk directory.

• —noMoveParanoia

Changed in version 3.2: Starting in 3.2, MongoDB uses —noMoveParanoia as the default.

During chunk migration, a shard does not save documents migrated fromthe shard.

TLS Options

See

Configure mongod and mongos for TLS/SSL for fulldocumentation of MongoDB’s support.

• —tlsMode <mode>

New in version 4.2.

Enables TLS used for all network connections. Theargument to the —tlsMode option can be one of the following:

ValueDescriptiondisabledThe server does not use TLS.allowTLSConnections between servers do not use TLS. For incomingconnections, the server accepts both TLS and non-TLS.preferTLSConnections between servers use TLS. For incomingconnections, the server accepts both TLS and non-TLS.requireTLSThe server uses and accepts only TLS encrypted connections.

If —tlsCAFile or tls.CAFile is notspecified and you are not using x.509 authentication, thesystem-wide CA certificate store will be used when connecting to anTLS-enabled server.

If using x.509 authentication, —tlsCAFile or tls.CAFilemust be specified unless using —tlsCertificateSelector.

For more information about TLS and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —tlsCertificateKeyFile <filename>

New in version 4.2.

Note

Starting in 4.0, on macOS or Windows, you can use a certificate fromthe operating system’s secure store instead of specifying a PEM file. See—tlsCertificateSelector.

Specifies the .pem file that contains both the TLS certificateand key.

• On Linux/BSD, you must specify —tlsCertificateKeyFile when TLS is enabled.
• On Windows or macOS, you must specify either —tlsCertificateKeyFile or—tlsCertificateSelector when TLS is enabled.For more information about TLS and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —tlsCertificateKeyFilePassword <value>

New in version 4.2.

Specifies the password to de-crypt the certificate-key file (i.e.—tlsCertificateKeyFile). Use the —tlsCertificateKeyFilePassword option only if thecertificate-key file is encrypted. In all cases, the mongod willredact the password from all logging and reporting output.

Starting in MongoDB 4.0:

• On Linux/BSD, if the private key in the PEM file is encrypted andyou do not specify the —tlsCertificateKeyFilePassword option, MongoDB will prompt for apassphrase. See TLS/SSL Certificate Passphrase.
• On macOS or Windows, if the private key in the PEM file isencrypted, you must explicitly specify the —tlsCertificateKeyFilePassword option.Alternatively, you can use a certificate from the secure systemstore (see —tlsCertificateSelector) instead of a PEM file or use anunencrypted PEM file.For more information about TLS and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —clusterAuthMode <option>
• Default: keyFile

New in version 2.6.

The authentication mode used for cluster authentication. If you useinternal x.509 authentication,specify so here. This option can have one of the following values:

ValueDescriptionkeyFileUse a keyfile for authentication.Accept only keyfiles.sendKeyFileFor rolling upgrade purposes. Send a keyfile forauthentication but can accept both keyfiles and x.509certificates.sendX509For rolling upgrade purposes. Send the x.509 certificate forauthentication but can accept both keyfiles and x.509certificates.x509Recommended. Send the x.509 certificate for authentication andaccept only x.509 certificates.

If —tlsCAFile or tls.CAFile is notspecified and you are not using x.509 authentication, thesystem-wide CA certificate store will be used when connecting to anTLS-enabled server.

If using x.509 authentication, —tlsCAFile or tls.CAFilemust be specified unless using —tlsCertificateSelector.

For more information about TLS and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —tlsClusterFile <filename>

New in version 4.2.

Note

Starting in 4.0, on macOS or Windows, you can use a certificatefrom the operating system’s secure store instead of a PEMfile. See —tlsClusterCertificateSelector.

Specifies the .pem file that contains the x.509 certificate-keyfile for membership authenticationfor the cluster or replica set.

If —tlsClusterFile does not specify the .pem file for internal clusterauthentication or the alternative—tlsClusterCertificateSelector, the cluster uses the.pem file specified in the —tlsCertificateKeyFile option orthe certificate returned by the —tlsCertificateSelector.

If using x.509 authentication, —tlsCAFile or tls.CAFilemust be specified unless using —tlsCertificateSelector.

For more information about TLS and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —tlsCertificateSelector <parameter>=<value>

New in version 4.2: Available on Windows and macOS as an alternative to —tlsCertificateKeyFile.

The —tlsCertificateKeyFile and —tlsCertificateSelector options are mutually exclusive. You can onlyspecify one.

Specifies a certificate property in order to select a matchingcertificate from the operating system’s certificate store.

—tlsCertificateSelector accepts an argument of the format <property>=<value>where the property can be one of the following:

PropertyValue typeDescriptionsubjectASCII stringSubject name or common name on certificatethumbprinthex stringA sequence of bytes, expressed as hexadecimal, used toidentify a public key by its SHA-1 digest.

The thumbprint is sometimes referred to as afingerprint.

When using the system SSL certificate store, OCSP (OnlineCertificate Status Protocol) is used to validate the revocationstatus of certificates.

• —tlsClusterCertificateSelector <parameter>=<value>

New in version 4.2: Available on Windows and macOS as an alternative to—tlsClusterFile.

—tlsClusterFile and —tlsClusterCertificateSelector options are mutually exclusive. You can onlyspecify one.

Specifies a certificate property in order to select a matchingcertificate from the operating system’s certificate store to use forinternal authentication.

—tlsClusterCertificateSelector accepts an argument of the format <property>=<value>where the property can be one of the following:

PropertyValue typeDescriptionsubjectASCII stringSubject name or common name on certificatethumbprinthex stringA sequence of bytes, expressed as hexadecimal, used toidentify a public key by its SHA-1 digest.

The thumbprint is sometimes referred to as afingerprint.

• —tlsClusterPassword <value>

New in version 4.2.

Specifies the password to de-crypt the x.509 certificate-key filespecified with —tlsClusterFile. Use the —tlsClusterPassword option onlyif the certificate-key file is encrypted. In all cases, the mongodwill redact the password from all logging and reporting output.

Starting in MongoDB 4.0:

• On Linux/BSD, if the private key in the x.509 file is encrypted andyou do not specify the —tlsClusterPassword option, MongoDB will prompt for apassphrase. See TLS/SSL Certificate Passphrase.
• On macOS or Windows, if the private key in the x.509 file isencrypted, you must explicitly specify the —tlsClusterPassword option.Alternatively, you can either use a certificate from the securesystem store (see —tlsClusterCertificateSelector) instead of a cluster PEM file oruse an unencrypted PEM file.For more information about TLS and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —tlsCAFile <filename>

New in version 4.2.

Specifies the .pem file that contains the root certificate chainfrom the Certificate Authority. Specify the file name of the.pem file using relative or absolute paths.

Starting in 4.0, on macOS or Windows, you can use a certificate fromthe operating system’s secure store instead of a PEM key file. See—tlsCertificateSelector. When using the secure store, youdo not need to, but can, also specify the —tlsCAFile.

For more information about TLS and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —tlsClusterCAFile <filename>

New in version 4.2.

Specifies the .pem file that contains the root certificate chainfrom the Certificate Authority used to validate the certificatepresented by a client establishing a connection. Specify the filename of the .pem file using relative or absolute paths.

If —tlsClusterCAFile does not specify the .pem file for validating thecertificate from a client establishing a connection, the cluster usesthe .pem file specified in the —tlsCAFile option.

—tlsClusterCAFile lets you use separate Certificate Authorities to verify theclient to server and server to client portions of the TLS handshake.

Starting in 4.0, on macOS or Windows, you can use a certificate fromthe operating system’s secure store instead of a PEM key file. See—tlsClusterCertificateSelector. When using the secure store, youdo not need to, but can, also specify the —tlsClusterCAFile.

Requires that —tlsCAFile is set.

For more information about TLS and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —tlsCRLFile <filename>

New in version 4.2.

Specifies the the .pem file that contains the Certificate RevocationList. Specify the file name of the .pem file using relative orabsolute paths.

Note

Starting in MongoDB 4.0, you cannot specify —tlsCRLFile on macOS. Use —tlsCertificateSelector instead.

For more information about TLS and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —tlsAllowInvalidCertificates

New in version 4.2.

Bypasses the validation checks for TLS certificates on otherservers in the cluster and allows the use of invalid certificates toconnect.

Note

If you specify—tlsAllowInvalidCertificates or tls.allowInvalidCertificates:true when using x.509 authentication, an invalid certificate isonly sufficient to establish a TLS connection but isinsufficient for authentication.

When usingthe —tlsAllowInvalidCertificates setting, MongoDBlogs a warning regarding the use of the invalid certificate.

For more information about TLS and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —tlsAllowInvalidHostnames

New in version 4.2.

Disables the validation of the hostnames in TLS certificates,when connecting to other members of the replica set or sharded clusterfor inter-process authentication. This allows mongod to connectto other members if the hostnames in their certificates do not matchtheir configured hostname.

For more information about TLS and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —tlsAllowConnectionsWithoutCertificates

New in version 4.2.

For clients that do not present certificates, mongod bypassesTLS/SSL certificate validation when establishing the connection.

For clients that present a certificate, however, mongod performscertificate validation using the root certificate chain specified by—tlsCAFile and reject clients with invalid certificates.

Use the —tlsAllowConnectionsWithoutCertificates option if you have a mixed deployment that includesclients that do not or cannot present certificates to the mongod.

For more information about TLS and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —tlsDisabledProtocols <protocol(s)>

New in version 4.2.

Prevents a MongoDB server running with TLS from acceptingincoming connections that use a specific protocol or protocols. Tospecify multiple protocols, use a comma separated list of protocols.

—tlsDisabledProtocols recognizes the following protocols: TLS1_0, TLS1_1,TLS1_2, and starting in version 4.0.4 (and 3.6.9), TLS1_3.

• On macOS, you cannot disable TLS1_1 and leave both TLS1_0 andTLS1_2 enabled. You must disable at least one of the othertwo, for example, TLS1_0,TLS1_1.
• To list multiple protocols, specify as a comma separated list ofprotocols. For example TLS1_0,TLS1_1.
• Specifying an unrecognized protocol will prevent the server fromstarting.
• The specified disabled protocols overrides any default disabledprotocols.Starting in version 4.0, MongoDB disables the use of TLS 1.0 if TLS1.1+ is available on the system. To enable the disabled TLS 1.0,specify none to —tlsDisabledProtocols. See Disable TLS 1.0.

Members of replica sets and sharded clusters must speak at least oneprotocol in common.

See also

Disallow Protocols

• —tlsFIPSMode

New in version 4.2.

Directs the mongod to use the FIPS mode of the TLSlibrary. Your system must have a FIPScompliant library to use the —tlsFIPSMode option.

Note

FIPS-compatible TLS/SSL isavailable only in MongoDB Enterprise. SeeConfigure MongoDB for FIPS for more information.

SSL Options (Deprecated)

Important

All SSL options are deprecated since 4.2. Use the TLS counterparts instead, as they have identical functionality to theSSL options. The SSL protocol is deprecated and MongoDB supports TLS 1.0and later.

See

Configure mongod and mongos for TLS/SSL for fulldocumentation of MongoDB’s support.

• —sslOnNormalPorts

Deprecated since version 2.6: Use —tlsMode requireTLS instead.

Enables TLS/SSL for mongod.

With —sslOnNormalPorts, a mongod requires TLS/SSL encryption for allconnections on the default MongoDB port, or the port specified by—port. By default, —sslOnNormalPorts isdisabled.

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —sslMode <mode>

Deprecated since version 4.2: Use —tlsMode instead.

New in version 2.6.

Enables TLS/SSL or mixed TLS/SSL used for all network connections. Theargument to the —sslMode option can be one of the following:

ValueDescriptiondisabledThe server does not use TLS/SSL.allowSSLConnections between servers do not use TLS/SSL. For incomingconnections, the server accepts both TLS/SSL and non-TLS/non-SSL.preferSSLConnections between servers use TLS/SSL. For incomingconnections, the server accepts both TLS/SSL and non-TLS/non-SSL.requireSSLThe server uses and accepts only TLS/SSL encrypted connections.

Starting in version 3.4, if —tlsCAFile/net.tls.CAFile (ortheir aliases —sslCAFile/net.ssl.CAFile) is not specifiedand you are not using x.509 authentication, the system-wide CAcertificate store will be used when connecting to an TLS/SSL-enabledserver.

To use x.509 authentication, —tlsCAFile or net.tls.CAFilemust be specified unless using —tlsCertificateSelector or—net.tls.certificateSelector. Or if using the ssl aliases,—sslCAFile or net.ssl.CAFile must be specified unless using—sslCertificateSelector or net.ssl.certificateSelector.

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —sslPEMKeyFile <filename>

Deprecated since version 4.2: Use —tlsCertificateKeyFile instead.

Note

Starting in 4.0, on macOS or Windows, you can use a certificate fromthe operating system’s secure store instead of a PEM file. See—sslCertificateSelector.

Specifies the .pem file that contains both the TLS/SSL certificateand key.

• On Linux/BSD, you must specify —sslPEMKeyFile when TLS/SSL is enabled.
• On Windows or macOS, you must specify either —sslPEMKeyFile or—sslCertificateSelector when TLS/SSL is enabled.For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —sslPEMKeyPassword <value>

Deprecated since version 4.2: Use —tlsCertificateKeyFilePassword instead.

Specifies the password to de-crypt the certificate-key file (i.e.—sslPEMKeyFile). Use the —sslPEMKeyPassword option only if thecertificate-key file is encrypted. In all cases, the mongod willredact the password from all logging and reporting output.

Starting in MongoDB 4.0:

• On Linux/BSD, if the private key in the PEM file is encrypted andyou do not specify the —sslPEMKeyPassword option, MongoDB will prompt for apassphrase. See TLS/SSL Certificate Passphrase.
• On macOS or Windows, if the private key in the PEM file isencrypted, you must explicitly specify the —sslPEMKeyPassword option.Alternatively, you can use a certificate from the secure systemstore (see —sslCertificateSelector) instead of a PEM key file or use anunencrypted PEM file.For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —sslClusterFile <filename>

Deprecated since version 4.2: Use —tlsClusterFile instead.

Note

Starting in 4.0, on macOS or Windows, you can use a certificatefrom the operating system’s secure store instead of a PEM keyfile. See —sslClusterCertificateSelector.

Specifies the .pem file that contains the x.509 certificate-keyfile for membership authenticationfor the cluster or replica set.

If —sslClusterFile does not specify the .pem file for internal clusterauthentication or the alternative—sslClusterCertificateSelector, the cluster uses the.pem file specified in the —sslPEMKeyFile option orthe certificate returned by the —sslCertificateSelector.

To use x.509 authentication, —tlsCAFile or net.tls.CAFilemust be specified unless using —tlsCertificateSelector or—net.tls.certificateSelector. Or if using the ssl aliases,—sslCAFile or net.ssl.CAFile must be specified unless using—sslCertificateSelector or net.ssl.certificateSelector.

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —sslCertificateSelector <parameter>=<value>

Deprecated since version 4.2: Use —tlsCertificateSelector instead.

New in version 4.0: Available on Windows and macOS as an alternative to —tlsCertificateKeyFile.

—tlsCertificateKeyFile and —sslCertificateSelector options are mutually exclusive. You can onlyspecify one.

Specifies a certificate property in order to select a matchingcertificate from the operating system’s certificate store.

—sslCertificateSelector accepts an argument of the format <property>=<value>where the property can be one of the following:

PropertyValue typeDescriptionsubjectASCII stringSubject name or common name on certificatethumbprinthex stringA sequence of bytes, expressed as hexadecimal, used toidentify a public key by its SHA-1 digest.

The thumbprint is sometimes referred to as afingerprint.

When using the system SSL certificate store, OCSP (OnlineCertificate Status Protocol) is used to validate the revocationstatus of certificates.

• —sslClusterCertificateSelector <parameter>=<value>

Deprecated since version 4.2: Use —tlsClusterCertificateSelector instead.

New in version 4.0: Available on Windows and macOS as an alternative to—sslClusterFile.

—sslClusterFile and —sslClusterCertificateSelector options are mutually exclusive. You can onlyspecify one.

Specifies a certificate property in order to select a matchingcertificate from the operating system’s certificate store to use forinternal authentication.

—sslClusterCertificateSelector accepts an argument of the format <property>=<value>where the property can be one of the following:

PropertyValue typeDescriptionsubjectASCII stringSubject name or common name on certificatethumbprinthex stringA sequence of bytes, expressed as hexadecimal, used toidentify a public key by its SHA-1 digest.

The thumbprint is sometimes referred to as afingerprint.

• —sslClusterPassword <value>

Deprecated since version 4.2: Use —tlsClusterPassword instead.

New in version 2.6.

Specifies the password to de-crypt the x.509 certificate-key filespecified with —sslClusterFile. Use the —sslClusterPassword option onlyif the certificate-key file is encrypted. In all cases, the mongodwill redact the password from all logging and reporting output.

Starting in MongoDB 4.0:

• On Linux/BSD, if the private key in the x.509 file is encrypted andyou do not specify the —sslClusterPassword option, MongoDB will prompt for apassphrase. See TLS/SSL Certificate Passphrase.
• On macOS or Windows, if the private key in the x.509 file isencrypted, you must explicitly specify the —sslClusterPassword option.Alternatively, you can either use a certificate from the securesystem store (see —sslClusterCertificateSelector) instead of a cluster PEM file oruse an unencrypted PEM file.For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —sslCAFile <filename>

Deprecated since version 4.2: Use —tlsCAFile instead.

Specifies the .pem file that contains the root certificate chainfrom the Certificate Authority. Specify the file name of the.pem file using relative or absolute paths.

Starting in 4.0, on macOS or Windows, you can use a certificate fromthe operating system’s secure store instead of a PEM key file. See—sslCertificateSelector. When using the secure store, youdo not need to, but can, also specify the —sslCAFile.

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —sslClusterCAFile <filename>

Deprecated since version 4.2: Use —tlsClusterCAFile instead.

Specifies the .pem file that contains the root certificate chainfrom the Certificate Authority used to validate the certificatepresented by a client establishing a connection. Specify the filename of the .pem file using relative or absolute paths.

If —sslClusterCAFile does not specify the .pem file for validating thecertificate from a client establishing a connection, the cluster usesthe .pem file specified in the —sslCAFile option.

—sslClusterCAFile lets you use separate Certificate Authorities to verify theclient to server and server to client portions of the TLS handshake.

Starting in 4.0, on macOS or Windows, you can use a certificate fromthe operating system’s secure store instead of a PEM key file. See—sslClusterCertificateSelector. When using the secure store, youdo not need to, but can, also specify the —sslClusterCAFile.

Requires that —sslCAFile is set.

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —sslCRLFile <filename>

Deprecated since version 4.2: Use —tlsCRLFile instead.

Specifies the the .pem file that contains the Certificate RevocationList. Specify the file name of the .pem file using relative orabsolute paths.

Note

Starting in MongoDB 4.0, you cannot specify —sslCRLFile on macOS. Use —sslCertificateSelector instead.

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —sslAllowInvalidCertificates

Deprecated since version 4.2: Use —tlsAllowInvalidCertificates instead.

Bypasses the validation checks for TLS/SSL certificates on otherservers in the cluster and allows the use of invalid certificates toconnect.

Note

Starting in MongoDB 4.0, if you specify—sslAllowInvalidCertificates ornet.ssl.allowInvalidCertificates: true (or in MongoDB 4.2, thealias —tlsAllowInvalidateCertificates ornet.tls.allowInvalidCertificates: true) when using x.509authentication, an invalid certificate is only sufficient toestablish a TLS/SSL connection but is insufficient forauthentication.

When usingthe —sslAllowInvalidCertificates setting, MongoDBlogs a warning regarding the use of the invalid certificate.

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —sslAllowInvalidHostnames

Deprecated since version 4.2: Use —tlsAllowInvalidHostnames instead.

New in version 3.0.

Disables the validation of the hostnames in TLS/SSL certificates,when connecting to other members of the replica set or sharded clusterfor inter-process authentication. This allows mongod to connectto other members if the hostnames in their certificates do not matchtheir configured hostname.

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —sslAllowConnectionsWithoutCertificates

Deprecated since version 4.2: Use —tlsAllowConnectionsWithoutCertificates instead.

For clients that do not present certificates, mongod bypassesTLS/SSL certificate validation when establishing the connection.

For clients that present a certificate, however, mongod performscertificate validation using the root certificate chain specified by—sslCAFile and reject clients with invalid certificates.

Use the —sslAllowConnectionsWithoutCertificates option if you have a mixed deployment that includesclients that do not or cannot present certificates to the mongod.

For more information about TLS/SSL and MongoDB, seeConfigure mongod and mongos for TLS/SSL andTLS/SSL Configuration for Clients .

• —sslDisabledProtocols <protocol(s)>

Deprecated since version 4.2: Use —tlsDisabledProtocols instead.

New in version 3.0.7.

Prevents a MongoDB server running with TLS/SSL from acceptingincoming connections that use a specific protocol or protocols. Tospecify multiple protocols, use a comma separated list of protocols.

—sslDisabledProtocols recognizes the following protocols: TLS1_0, TLS1_1,TLS1_2, and starting in version 4.0.4 (and 3.6.9), TLS1_3.

• On macOS, you cannot disable TLS1_1 and leave both TLS1_0 andTLS1_2 enabled. You must disable at least one of the othertwo, for example, TLS1_0,TLS1_1.
• To list multiple protocols, specify as a comma separated list ofprotocols. For example TLS1_0,TLS1_1.
• Specifying an unrecognized protocol will prevent the server fromstarting.
• The specified disabled protocols overrides any default disabledprotocols.Starting in version 4.0, MongoDB disables the use of TLS 1.0 if TLS1.1+ is available on the system. To enable the disabled TLS 1.0,specify none to —sslDisabledProtocols. See Disable TLS 1.0.

Members of replica sets and sharded clusters must speak at least oneprotocol in common.

See also

Disallow Protocols

• —sslFIPSMode

Deprecated since version 4.2: Use —tlsFIPSMode instead.

Directs the mongod to use the FIPS mode of the TLS/SSLlibrary. Your system must have a FIPScompliant library to use the —sslFIPSMode option.

Note

FIPS-compatible TLS/SSL isavailable only in MongoDB Enterprise. SeeConfigure MongoDB for FIPS for more information.

Profiler Options

• —profile <level>
• Default: 0

Configures the database profiler level.The following profiler levels are available:

LevelDescription0The profiler is off and does not collect any data.This is the default profiler level.1The profiler collects data for operations that take longerthan the value of slowms.2The profiler collects data for all operations.

Important

Profiling can impact performance and shares settings with the systemlog. Carefully consider any performance and security implicationsbefore configuring and enabling the profiler on a productiondeployment.

See Profiler Overhead for more information onpotential performance degradation.

• —slowms <integer>
• Default: 100

The slow operation time threshold, in milliseconds. Operationsthat run for longer than this threshold are considered slow.

When logLevel is set to 0, MongoDB records _slow_operations to the diagnostic log at a rate determined byslowOpSampleRate. Starting in MongoDB4.2, the secondaries of replica sets log all oplog entry messagesthat take longer than the slow operation threshold to apply regardless of the sample rate.

At higher logLevel settings, all operations appear inthe diagnostic log regardless of their latency with the followingexception: the logging of slow oplog entry messages by thesecondaries. The secondaries log only the slow oplogentries; increasing the logLevel does not log alloplog entries.

For mongod instances, —slowms affects the diagnostic logand, if enabled, the profiler.

See also

Database Profiler

• —slowOpSampleRate <double>
• Default: 1.0

The fraction of slow operations that should be profiled or logged.—slowOpSampleRate accepts values between 0 and 1, inclusive.

—slowOpSampleRate does not affect the slow oplog entry logging by the secondary members of a replica set. Secondarymembers log all oplog entries that take longer than the slowoperation threshold regardless of the —slowOpSampleRate.

For mongod instances, —slowOpSampleRate affects thediagnostic log and, if enabled, the profiler.

Audit Options

• —auditDestination
• Enables auditing and specifies wheremongod sends all audit events.

—auditDestination can have one of the following values:

ValueDescriptionsyslogOutput the audit events to syslog in JSON format. Not available onWindows. Audit messages have a syslog severity level of infoand a facility level of user.

The syslog message limit can result in the truncation ofaudit messages. The auditing system will neither detect thetruncation nor error upon its occurrence.consoleOutput the audit events to stdout in JSON format.fileOutput the audit events to the file specified in—auditPath in the format specified in—auditFormat.

Note

Available only in MongoDB Enterpriseand MongoDB Atlas.

• —auditFormat

New in version 2.6.

Specifies the format of the output file for auditing if —auditDestination is file. The—auditFormat option can have one of the following values:

ValueDescriptionJSONOutput the audit events in JSON format to the file specifiedin —auditPath.BSONOutput the audit events in BSON binary format to the filespecified in —auditPath.

Printing audit events to a file in JSON format degrades serverperformance more than printing to a file in BSON format.

Note

Available only in MongoDB Enterpriseand MongoDB Atlas.

• —auditPath

New in version 2.6.

Specifies the output file for auditing if—auditDestination has value of file. The —auditPathoption can take either a full path name or a relative path name.

Note

Available only in MongoDB Enterpriseand MongoDB Atlas.

• —auditFilter

New in version 2.6.

Specifies the filter to limit the types of operations the audit system records. The option takes a string representationof a query document of the form:

{ <field1>: <expression1>, ... }

The <field> can be any field in the audit message, including fields returned in theparam document. The<expression> is a query condition expression.

To specify an audit filter, enclose the filter document in singlequotes to pass the document as a string.

To specify the audit filter in a configuration file, you must use the YAML format ofthe configuration file.

Note

Available only in MongoDB Enterpriseand MongoDB Atlas.

SNMP Options

Note

MongoDB Enterprise on macOS does not include support for SNMP dueto SERVER-29352.

• —snmp-disabled
• Disables SNMP access to mongod. The option is incompatiblewith —snmp-subagent and —snmp-master.

New in version 4.0.6.

• —snmp-subagent
• Runs SNMP as a subagent. The option is incompatible with —snmp-disabled.

• —snmp-master
• Runs SNMP as a master. The option is incompatible with —snmp-disabled.

See also

• Monitor MongoDB With SNMP on Linux
• Monitor MongoDB Windows with SNMP
• Troubleshoot SNMP

inMemory Options

• —inMemorySizeGB <float>
• Default: 50% of physical RAM less 1 GB

Changed in version 3.4: Values can range from 256MB to 10TB and can be a float.

Maximum amount of memory to allocate for in-memory storageengine data, including indexes, oplog if themongod is part of replica set, replica set or shardedcluster metadata, etc.

By default, the in-memory storage engine uses 50% of physical RAM minus1 GB.

Enterprise Feature

Available in MongoDB Enterprise only.

Encryption Key Management Options

• —enableEncryption <boolean>
• Default: False

New in version 3.2.

Enables encryption for the WiredTiger storage engine. You must setto true to pass in encryption keys and configurations.

Enterprise Feature

Available in MongoDB Enterprise only.

• —encryptionCipherMode <string>
• Default: AES256-CBC

New in version 3.2.

The cipher mode to use for encryption at rest:

ModeDescriptionAES256-CBC256-bit Advanced Encryption Standard in Cipher Block ChainingModeAES256-GCM256-bit Advanced Encryption Standard in Galois/Counter Mode

Changed in version 4.0: MongoDB Enterprise on Windows no longer supports AES256-GCM. Thiscipher is now available only on Linux.

Enterprise Feature

Available in MongoDB Enterprise only.

• —encryptionKeyFile <string>

New in version 3.2.

The path to the local keyfile when managing keys via process otherthan KMIP. Only set when managing keys via process other than KMIP.If data is already encrypted using KMIP, MongoDB will throw an error.

The keyfile can contain only a single key. The key is either a 16 or32 character string.

Requires enableEncryption to be true.

Enterprise Feature

Available in MongoDB Enterprise only.

• —kmipKeyIdentifier <string>

New in version 3.2.

Unique KMIP identifier for an existing key within the KMIP server.Include to use the key associated with the identifier as the systemkey. You can only use the setting the first time you enableencryption for the mongod instance. RequiresenableEncryption to be true.

If unspecified, MongoDB will request that the KMIP server create anew key to utilize as the system key.

If the KMIP server cannot locate a key with the specified identifieror the data is already encrypted with a key, MongoDB will throw anerror

Enterprise Feature

Available in MongoDB Enterprise only.

• —kmipRotateMasterKey <boolean>
• Default: False

New in version 3.2.

If true, rotate the master key and re-encrypt the internalkeystore.

Enterprise Feature

Available in MongoDB Enterprise only.

See also

KMIP Master Key Rotation

• —kmipServerName <string>

New in version 3.2.

Hostname or IP address of key management solution running a KMIPserver. Requires enableEncryption to be true.

When connecting to the KMIP server, the mongodverifies that the specified —kmipServerName matches the Subject AlternativeName SAN (or, if SAN is not present, the Common Name CN)in the certificate presented by the KMIP server. If SAN ispresent, mongod does not match against the CN. Ifthe hostname does not match the SAN (or CN), themongod will fail to connect.

Starting in MongoDB 4.2, when performing comparison of SAN, MongoDBsupports comparison of DNS names or IP addresses. In previous versions,MongoDB only supports comparisons of DNS names.

Enterprise Feature

Available in MongoDB Enterprise only.

• —kmipPort <number>
• Default: 5696

New in version 3.2.

Port number the KMIP server is listening on. Requires that akmipServerName be provided. RequiresenableEncryption to be true.

Enterprise Feature

Available in MongoDB Enterprise only.

• —kmipClientCertificateSelector <string>

New in version 4.0: Available on Windows and macOS as an alternative to—kmipClientCertificateFile.

—kmipClientCertificateFile and —kmipClientCertificateSelector options are mutually exclusive. You can onlyspecify one.

Specifies a certificate property in order to select a matchingcertificate from the operating system’s certificate store toauthenticate MongoDB to the KMIP server.

—kmipClientCertificateSelector accepts an argument of the format <property>=<value>where the property can be one of the following:

PropertyValue typeDescriptionsubjectASCII stringSubject name or common name on certificatethumbprinthex stringA sequence of bytes, expressed as hexadecimal, used toidentify a public key by its SHA-1 digest.

The thumbprint is sometimes referred to as afingerprint.

Enterprise Feature

Available in MongoDB Enterprise only.

• —kmipClientCertificateFile <string>

New in version 3.2.

String containing the path to the client certificate used forauthenticating MongoDB to the KMIP server. Requires that akmipServerName be provided.

Note

Starting in 4.0, on macOS or Windows, you can use a certificatefrom the operating system’s secure store instead of a PEM keyfile. See —kmipClientCertificateSelector.

Enterprise Feature

Available in MongoDB Enterprise only.

• —kmipClientCertificatePassword <string>

New in version 3.2.

The password (if one exists) for the client certificate passed intokmipClientCertificateFile. Is used forauthenticating MongoDB to the KMIP server. Requires that akmipClientCertificateFile be provided.

Enterprise Feature

Available in MongoDB Enterprise only.

• —kmipServerCAFile <string>

New in version 3.2.

Path to CA File. Used for validating secure client connection toKMIP server.

Note

Starting in 4.0, on macOS or Windows, you can use a certificatefrom the operating system’s secure store instead of a PEM keyfile. See —kmipClientCertificateSelector. When using the secure store, you do notneed to, but can, also specify the —kmipServerCAFile.

• —eseDatabaseKeyRollover

New in version 4.2.

Roll over the encrypted storage engine database keys configured withAES256-GCM cipher.

When mongod instance is started with this option, theinstance rotates the keys and exits.

Enterprise Feature

Available in MongoDB Enterprise only.