The capacity of a TiKV cluster can be increased or decreased without interrupting the online services.

This document describes how to scale the TiKV and PD using TiUP.

For example, assume that the topology of the cluster is as follows:

Scale out a TiKV node

If you want to add a TiKV node to the 10.0.1.8 host, take the following steps.

1. Configure the scale-out topology:

   Put the following content in the scale-out-tikv.yaml file:

   tikv_servers:
   - host: 10.0.1.8
       ssh_port: 22
       port: 20160
       status_port: 20180
       deploy_dir: /data/deploy/install/deploy/tikv-20160
       data_dir: /data/deploy/install/data/tikv-20160
       log_dir: /data/deploy/install/log/tikv-20160

   To view the configuration of the current cluster, run tiup cluster edit-config <cluster-name>. Because the parameter configuration of global and server_configs is inherited by scale-out-tikv.yaml and thus also takes effect in scale-out-tikv.yaml.

2. Run the scale-out command:

   tiup cluster scale-out <cluster-name> scale-out-tikv.yaml

   If you see the Scaled cluster <cluster-name> out successfully, the scale-out operation is successfully completed.

3. Check the cluster status:

   tiup cluster display <cluster-name>

   Access the monitoring platform at http://10.0.1.1:3000 using your browser to monitor the status of the cluster and the new node.

After the scale-out, the cluster topology is as follows:

Scale out a PD node

If you want to add a PD node to the 10.0.1.9 host, take the following steps.

1. Configure the scale-out topology:

   Put the following content in the scale-out-pd.yaml file:

   pd_servers:
   - host: 10.0.1.9
       ssh_port: 22
       client_port: 2379
       peer_port: 2380
       deploy_dir: /data/deploy/install/deploy/pd-2379
       data_dir: /data/deploy/install/data/pd-2379
       log_dir: /data/deploy/install/log/pd-2379

   To view the configuration of the current cluster, run tiup cluster edit-config <cluster-name>. Because the parameter configuration of global and server_configs is inherited by scale-out-pd.yaml and thus also takes effect in scale-out-pd.yaml.

2. Run the scale-out command:

   tiup cluster scale-out <cluster-name> scale-out-pd.yaml

   If you see the Scaled cluster <cluster-name> out successfully, the scale-out operation is successfully completed.

3. Check the cluster status:

   tiup cluster display <cluster-name>

   Access the monitoring platform at http://10.0.1.1:3000 using your browser to monitor the status of the cluster and the new node.

After the scale-out, the cluster topology is as follows:

Scale in a TiKV cluster

If you want to remove a TiKV node from the 10.0.1.5 host, take the following steps.

You can take similar steps to remove the PD node.

1. View the node ID information:

   tiup cluster display <cluster-name>

2. Run the scale-in command:

   tiup cluster scale-in <cluster-name> --node 10.0.1.5:20160

   The --node parameter is the ID of the node to be taken offline.

   If you see the Scaled cluster <cluster-name> in successfully, the scale-in operation is successfully completed.

3. Check the cluster status:

   The scale-in process takes some time. If the status of the node to be scaled in becomes Tombstone, that means the scale-in operation is successful.

   To check the scale-in status, run the following command:

   tiup cluster display <cluster-name>

   Access the monitoring platform at http://10.0.1.1:3000 using your browser, and view the status of the cluster.

After the scale-in, the current topology is as follows: