MDS Config Reference

mds cache memory limit

  • Description

  • The memory limit the MDS should enforce for its cache.

  • Type

  • 64-bit Integer Unsigned

  • Default

  • 4G

mds cache reservation

  • Description

  • The cache reservation (memory or inodes) for the MDS cache to maintain.Once the MDS begins dipping into its reservation, it will recallclient state until its cache size shrinks to restore thereservation.

  • Type

  • Float

  • Default

  • 0.05

mds cache mid

  • Description

  • The insertion point for new items in the cache LRU(from the top).

  • Type

  • Float

  • Default

  • 0.7

mds dir commit ratio

  • Description

  • The fraction of directory that is dirty before Ceph commits usinga full update (instead of partial update).

  • Type

  • Float

  • Default

  • 0.5

mds dir max commit size

  • Description

  • The maximum size of a directory update before Ceph breaks it intosmaller transactions) (MB).

  • Type

  • 32-bit Integer

  • Default

  • 90

mds decay halflife

  • Description

  • The half-life of MDS cache temperature.

  • Type

  • Float

  • Default

  • 5

mds beacon interval

  • Description

  • The frequency (in seconds) of beacon messages sentto the monitor.

  • Type

  • Float

  • Default

  • 4

mds beacon grace

  • Description

  • The interval without beacons before Ceph declares an MDS laggy(and possibly replace it).

  • Type

  • Float

  • Default

  • 15

mds blacklist interval

  • Description

  • The blacklist duration for failed MDSs in the OSD map. Note,this controls how long failed MDS daemons will stay in theOSDMap blacklist. It has no effect on how long something isblacklisted when the administrator blacklists it manually. Forexample, ceph osd blacklist add will still use the defaultblacklist time.

  • Type

  • Float

  • Default

  • 24.0*60.0

mds reconnect timeout

  • Description

  • The interval (in seconds) to wait for clients to reconnectduring MDS restart.

  • Type

  • Float

  • Default

  • 45

mds tick interval

  • Description

  • How frequently the MDS performs internal periodic tasks.

  • Type

  • Float

  • Default

  • 5

mds dirstat min interval

  • Description

  • The minimum interval (in seconds) to try to avoid propagatingrecursive stats up the tree.

  • Type

  • Float

  • Default

  • 1

mds scatter nudge interval

  • Description

  • How quickly dirstat changes propagate up.

  • Type

  • Float

  • Default

  • 5

mds client prealloc inos

  • Description

  • The number of inode numbers to preallocate per client session.

  • Type

  • 32-bit Integer

  • Default

  • 1000

mds early reply

  • Description

  • Determines whether the MDS should allow clients to see requestresults before they commit to the journal.

  • Type

  • Boolean

  • Default

  • true

mds default dir hash

  • Description

  • The function to use for hashing files across directory fragments.

  • Type

  • 32-bit Integer

  • Default

  • 2 (i.e., rjenkins)

mds log skip corrupt events

  • Description

  • Determines whether the MDS should try to skip corrupt journalevents during journal replay.

  • Type

  • Boolean

  • Default

  • false

mds log max events

  • Description

  • The maximum events in the journal before we initiate trimming.Set to -1 to disable limits.

  • Type

  • 32-bit Integer

  • Default

  • -1

mds log max segments

  • Description

  • The maximum number of segments (objects) in the journal beforewe initiate trimming. Set to -1 to disable limits.

  • Type

  • 32-bit Integer

  • Default

  • 128

mds bal sample interval

  • Description

  • Determines how frequently to sample directory temperature(for fragmentation decisions).

  • Type

  • Float

  • Default

  • 3

mds bal replicate threshold

  • Description

  • The maximum temperature before Ceph attempts to replicatemetadata to other nodes.

  • Type

  • Float

  • Default

  • 8000

mds bal unreplicate threshold

  • Description

  • The minimum temperature before Ceph stops replicatingmetadata to other nodes.

  • Type

  • Float

  • Default

  • 0

mds bal split size

  • Description

  • The maximum directory size before the MDS will split a directoryfragment into smaller bits.

  • Type

  • 32-bit Integer

  • Default

  • 10000

mds bal split rd

  • Description

  • The maximum directory read temperature before Ceph splitsa directory fragment.

  • Type

  • Float

  • Default

  • 25000

mds bal split wr

  • Description

  • The maximum directory write temperature before Ceph splitsa directory fragment.

  • Type

  • Float

  • Default

  • 10000

mds bal split bits

  • Description

  • The number of bits by which to split a directory fragment.

  • Type

  • 32-bit Integer

  • Default

  • 3

mds bal merge size

  • Description

  • The minimum directory size before Ceph tries to mergeadjacent directory fragments.

  • Type

  • 32-bit Integer

  • Default

  • 50

mds bal interval

  • Description

  • The frequency (in seconds) of workload exchanges between MDSs.

  • Type

  • 32-bit Integer

  • Default

  • 10

mds bal fragment interval

  • Description

  • The delay (in seconds) between a fragment being eligible for splitor merge and executing the fragmentation change.

  • Type

  • 32-bit Integer

  • Default

  • 5

mds bal fragment fast factor

  • Description

  • The ratio by which frags may exceed the split size beforea split is executed immediately (skipping the fragment interval)

  • Type

  • Float

  • Default

  • 1.5

mds bal fragment size max

  • Description

  • The maximum size of a fragment before any new entriesare rejected with ENOSPC.

  • Type

  • 32-bit Integer

  • Default

  • 100000

mds bal idle threshold

  • Description

  • The minimum temperature before Ceph migrates a subtreeback to its parent.

  • Type

  • Float

  • Default

  • 0

mds bal max

  • Description

  • The number of iterations to run balancer before Ceph stops.(used for testing purposes only)

  • Type

  • 32-bit Integer

  • Default

  • -1

mds bal max until

  • Description

  • The number of seconds to run balancer before Ceph stops.(used for testing purposes only)

  • Type

  • 32-bit Integer

  • Default

  • -1

mds bal mode

  • Description

  • The method for calculating MDS load.

    • 0 = Hybrid.

    • 1 = Request rate and latency.

    • 2 = CPU load.

  • Type

  • 32-bit Integer

  • Default

  • 0

mds bal min rebalance

  • Description

  • The minimum subtree temperature before Ceph migrates.

  • Type

  • Float

  • Default

  • 0.1

mds bal min start

  • Description

  • The minimum subtree temperature before Ceph searches a subtree.

  • Type

  • Float

  • Default

  • 0.2

mds bal need min

  • Description

  • The minimum fraction of target subtree size to accept.

  • Type

  • Float

  • Default

  • 0.8

mds bal need max

  • Description

  • The maximum fraction of target subtree size to accept.

  • Type

  • Float

  • Default

  • 1.2

mds bal midchunk

  • Description

  • Ceph will migrate any subtree that is larger than this fractionof the target subtree size.

  • Type

  • Float

  • Default

  • 0.3

mds bal minchunk

  • Description

  • Ceph will ignore any subtree that is smaller than this fractionof the target subtree size.

  • Type

  • Float

  • Default

  • 0.001

mds bal target removal min

  • Description

  • The minimum number of balancer iterations before Ceph removesan old MDS target from the MDS map.

  • Type

  • 32-bit Integer

  • Default

  • 5

mds bal target removal max

  • Description

  • The maximum number of balancer iteration before Ceph removesan old MDS target from the MDS map.

  • Type

  • 32-bit Integer

  • Default

  • 10

mds replay interval

  • Description

  • The journal poll interval when in standby-replay mode.(“hot standby”)

  • Type

  • Float

  • Default

  • 1

mds shutdown check

  • Description

  • The interval for polling the cache during MDS shutdown.

  • Type

  • 32-bit Integer

  • Default

  • 0

mds thrash exports

  • Description

  • Ceph will randomly export subtrees between nodes (testing only).

  • Type

  • 32-bit Integer

  • Default

  • 0

mds thrash fragments

  • Description

  • Ceph will randomly fragment or merge directories.

  • Type

  • 32-bit Integer

  • Default

  • 0

mds dump cache on map

  • Description

  • Ceph will dump the MDS cache contents to a file on each MDSMap.

  • Type

  • Boolean

  • Default

  • false

mds dump cache after rejoin

  • Description

  • Ceph will dump MDS cache contents to a file afterrejoining the cache (during recovery).

  • Type

  • Boolean

  • Default

  • false

mds verify scatter

  • Description

  • Ceph will assert that various scatter/gather invariantsare true (developers only).

  • Type

  • Boolean

  • Default

  • false

mds debug scatterstat

  • Description

  • Ceph will assert that various recursive stat invariantsare true (for developers only).

  • Type

  • Boolean

  • Default

  • false

mds debug frag

  • Description

  • Ceph will verify directory fragmentation invariantswhen convenient (developers only).

  • Type

  • Boolean

  • Default

  • false

mds debug auth pins

  • Description

  • The debug auth pin invariants (for developers only).

  • Type

  • Boolean

  • Default

  • false

mds debug subtrees

  • Description

  • The debug subtree invariants (for developers only).

  • Type

  • Boolean

  • Default

  • false

mds kill mdstable at

  • Description

  • Ceph will inject MDS failure in MDSTable code(for developers only).

  • Type

  • 32-bit Integer

  • Default

  • 0

mds kill export at

  • Description

  • Ceph will inject MDS failure in the subtree export code(for developers only).

  • Type

  • 32-bit Integer

  • Default

  • 0

mds kill import at

  • Description

  • Ceph will inject MDS failure in the subtree import code(for developers only).

  • Type

  • 32-bit Integer

  • Default

  • 0

mds kill link at

  • Description

  • Ceph will inject MDS failure in hard link code(for developers only).

  • Type

  • 32-bit Integer

  • Default

  • 0

mds kill rename at

  • Description

  • Ceph will inject MDS failure in the rename code(for developers only).

  • Type

  • 32-bit Integer

  • Default

  • 0

mds wipe sessions

  • Description

  • Ceph will delete all client sessions on startup(for testing only).

  • Type

  • Boolean

  • Default

  • false

mds wipe ino prealloc

  • Description

  • Ceph will delete ino preallocation metadata on startup(for testing only).

  • Type

  • Boolean

  • Default

  • false

mds skip ino

  • Description

  • The number of inode numbers to skip on startup(for testing only).

  • Type

  • 32-bit Integer

  • Default

  • 0

mds min caps per client

  • Description

  • Set the minimum number of capabilities a client may hold.

  • Type

  • Integer

  • Default

  • 100

mds max ratio caps per client

  • Description

  • Set the maximum ratio of current caps that may be recalled during MDS cache pressure.

  • Type

  • Float

  • Default

  • 0.8