Scale PD Microservices Nodes Using TiUP

This document describes how to scale PD microservice nodes (including TSO and Scheduling nodes) in a cluster and how to switch the PD working mode using TiUP.

To view the current cluster name list, run tiup cluster list.

For example, the original topology of the cluster is as follows:

Host IPService
10.0.1.4TiDB + PD
10.0.1.5TiKV + Monitor
10.0.1.1TiKV
10.0.1.2TiKV
10.0.1.6TSO
10.0.1.7Scheduling

Add TSO/Scheduling nodes

This section exemplifies how to add a TSO node (at IP address 10.0.1.8) and a Scheduling node (at IP address 10.0.1.9) to a TiDB cluster with PD microservices enabled.

1. Configure the scale-out topology

Add the scale-out topology configuration in the scale-out.yml file:

vi scale-out.yml

The following is the configuration example for the TSO node:

tso_servers: - host: 10.0.1.8 port: 3379

The following is the configuration example for the Scheduling node:

scheduling_servers: - host: 10.0.1.9 port: 3379

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.yml, it also takes effect in scale-out.yml.

2. Run the scale-out command

Before you run the scale-out command, use the check and check --apply commands to detect and automatically repair potential risks in the cluster:

  1. Check for potential risks:

    tiup cluster check <cluster-name> scale-out.yml --cluster --user root [-p] [-i /home/root/.ssh/gcp_rsa]
  2. Enable automatic repair:

    tiup cluster check <cluster-name> scale-out.yml --cluster --apply --user root [-p] [-i /home/root/.ssh/gcp_rsa]
  3. Run the scale-out command:

    tiup cluster scale-out <cluster-name> scale-out.yml [-p] [-i /home/root/.ssh/gcp_rsa]

In the preceding commands:

  • scale-out.yml is the scale-out configuration file.
  • --user root indicates logging in to the target machine as the root user to complete the cluster scale out. The root user is expected to have ssh and sudo privileges to the target machine. Alternatively, you can use other users with ssh and sudo privileges to complete the deployment.
  • [-i] and [-p] are optional. If you have configured login to the target machine without a password, these parameters are not required. If not, choose one of the two parameters. [-i] is the private key of the root user (or other users specified by --user) that has access to the target machine. [-p] is used to input the user password interactively.

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

3. Check the cluster status

tiup cluster display <cluster-name>

Access the monitoring platform at http://10.0.1.5:3000 using your browser to monitor the status of the cluster and the new nodes.

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

Host IPService
10.0.1.4TiDB + PD
10.0.1.5TiKV + Monitor
10.0.1.1TiKV
10.0.1.2TiKV
10.0.1.6TSO
10.0.1.7Scheduling
10.0.1.8TSO
10.0.1.9Scheduling

Remove TSO/Scheduling nodes

This section exemplifies how to remove a TSO node (at IP address 10.0.1.8) and a Scheduling node (at IP address 10.0.1.9) from a TiDB cluster with multiple TSO or Scheduling nodes.

1. View the node ID information

tiup cluster display <cluster-name>
Starting /root/.tiup/components/cluster/v1.16/cluster display <cluster-name> TiDB Cluster: <cluster-name> TiDB Version: v8.2.0 ID Role Host Ports Status Data Dir Deploy Dir -- ---- ---- ----- ------ -------- ---------- 10.0.1.4:2379 pd 10.0.1.4 2379/2380 Healthy data/pd-2379 deploy/pd-2379 10.0.1.1:20160 tikv 10.0.1.1 20160/20180 Up data/tikv-20160 deploy/tikv-20160 10.0.1.2:20160 tikv 10.0.1.2 20160/20180 Up data/tikv-20160 deploy/tikv-20160 10.0.1.5:20160 tikv 10.0.1.5 20160/20180 Up data/tikv-20160 deploy/tikv-20160 10.0.1.4:4000 tidb 10.0.1.4 4000/10080 Up - deploy/tidb-4000 10.0.1.5:9090 prometheus 10.0.1.5 9090 Up data/prometheus-9090 deploy/prometheus-9090 10.0.1.5:3000 grafana 10.0.1.5 3000 Up - deploy/grafana-3000 10.0.1.5:9093 alertmanager 10.0.1.5 9093/9094 Up data/alertmanager-9093 deploy/alertmanager-9093 10.0.1.6:3379 tso 10.0.1.6 3379 Up|P data/tso-3379 deploy/tso-3379 10.0.1.8:3379 tso 10.0.1.8 3379 Up data/tso-3379 deploy/tso-3379 10.0.1.7:3379 scheduling 10.0.1.7 3379 Up|P data/scheduling-3379 deploy/scheduling-3379 10.0.1.9:3379 scheduling 10.0.1.9 3379 Up data/scheduling-3379 deploy/scheduling-3379

2. Run scale-in commands

tiup cluster scale-in <cluster-name> --node 10.0.1.8:3379 tiup cluster scale-in <cluster-name> --node 10.0.1.9:3379

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

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

3. Check the cluster status

Run the following command to check if the nodes are successfully removed:

tiup cluster display <cluster-name>

Access the monitoring platform at http://10.0.1.5:3000 using your browser to monitor the status of the entire cluster.

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

Host IPService
10.0.1.4TiDB + PD
10.0.1.5TiKV + Monitor
10.0.1.1TiKV
10.0.1.2TiKV
10.0.1.6TSO
10.0.1.7Scheduling

Switch the PD working mode

You can switch PD services between the following two working modes:

  • Regular mode: provides routing service, timestamp allocation, and cluster scheduling functions solely by PD nodes.
  • Microservice mode: enables you to deploy the PD timestamp allocation function to TSO nodes (providing tso microservices) and the cluster scheduling function to Scheduling nodes (providing scheduling microservices) separately. In this way, these two functions are decoupled from the routing function of PD, which allows PD nodes to focus on the routing service for metadata.

Switch from regular mode to microservices mode

For a cluster that has not enabled PD microservices, you can switch it to PD microservice mode and add a TSO node (at IP address 10.0.1.8) and a Scheduling node (at IP address 10.0.1.9) to it as follows:

  1. Add the scale-out topology configuration in the scale-out.yml file:

    vi scale-out.yml

    The following is a configuration example:

    tso_servers: - host: 10.0.1.8 port: 3379 scheduling_servers: - host: 10.0.1.9 port: 3379
  2. Modify the cluster configuration and switch the cluster to PD microservice mode:

    tiup cluster edit-config <cluster-name>

    Add pd_mode: ms to global:

    global: user: tidb ssh_port: 22 listen_host: 0.0.0.0 deploy_dir: /tidb-deploy data_dir: /tidb-data os: linux arch: amd64 systemd_mode: system pd_mode: ms
  3. Perform a rolling update of the PD node configuration:

    tiup cluster reload <cluster-name> -R pd
  4. Run the scale-out command to add PD microservice nodes:

    tiup cluster scale-out <cluster-name> scale-out.yml

Switch from microservices mode to regular mode

For a cluster with PD microservices enabled (assume that it has a TSO node at IP address 10.0.1.8 and a Scheduling node at IP address 10.0.1.9), you can switch it to non-microservice mode as follows:

  1. Modify the cluster configuration and switch the cluster to non-microservice mode:

    tiup cluster edit-config <cluster-name>

    Remove pd_mode: ms from global:

    global: user: tidb ssh_port: 22 listen_host: 0.0.0.0 deploy_dir: /tidb-deploy data_dir: /tidb-data os: linux arch: amd64 systemd_mode: system
  2. Run the scale-in command to remove all PD microservice nodes:

    tiup cluster scale-in <cluster-name> --node 10.0.1.8:3379,10.0.1.9:3379
  3. Perform a rolling update of the PD node configuration:

    tiup cluster reload <cluster-name> -R pd

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