Scale the TiDB Cluster Using TiDB-Ansible
The capacity of a TiDB cluster can be increased or decreased without affecting the online services.
Warning:
In decreasing the capacity, if your cluster has a mixed deployment of other services, do not perform the following procedures. The following examples assume that the removed nodes have no mixed deployment of other services.
Assume that the topology is as follows:
| Name | Host IP | Services |
|---|---|---|
| node1 | 172.16.10.1 | PD1 |
| node2 | 172.16.10.2 | PD2 |
| node3 | 172.16.10.3 | PD3, Monitor |
| node4 | 172.16.10.4 | TiDB1 |
| node5 | 172.16.10.5 | TiDB2 |
| node6 | 172.16.10.6 | TiKV1 |
| node7 | 172.16.10.7 | TiKV2 |
| node8 | 172.16.10.8 | TiKV3 |
| node9 | 172.16.10.9 | TiKV4 |
Increase the capacity of a TiDB/TiKV node
For example, if you want to add two TiDB nodes (node101, node102) with the IP addresses 172.16.10.101 and 172.16.10.102, take the following steps:
Edit the
inventory.inifile and append the node information:[tidb_servers] 172.16.10.4 172.16.10.5 172.16.10.101 172.16.10.102 [pd_servers] 172.16.10.1 172.16.10.2 172.16.10.3 [tikv_servers] 172.16.10.6 172.16.10.7 172.16.10.8 172.16.10.9 [monitored_servers] 172.16.10.1 172.16.10.2 172.16.10.3 172.16.10.4 172.16.10.5 172.16.10.6 172.16.10.7 172.16.10.8 172.16.10.9 172.16.10.101 172.16.10.102 [monitoring_servers] 172.16.10.3 [grafana_servers] 172.16.10.3Now the topology is as follows:
Name Host IP Services node1 172.16.10.1 PD1 node2 172.16.10.2 PD2 node3 172.16.10.3 PD3, Monitor node4 172.16.10.4 TiDB1 node5 172.16.10.5 TiDB2 node101 172.16.10.101 TiDB3 node102 172.16.10.102 TiDB4 node6 172.16.10.6 TiKV1 node7 172.16.10.7 TiKV2 node8 172.16.10.8 TiKV3 node9 172.16.10.9 TiKV4 Initialize the newly added node:
ansible-playbook bootstrap.yml -l 172.16.10.101,172.16.10.102
Note:
If an alias is configured in the
inventory.inifile, for example,node101 ansible_host=172.16.10.101, use-lto specify the alias when executingansible-playbook. For example,ansible-playbook bootstrap.yml -l node101,node102. This also applies to the following steps.Deploy the newly added node:
ansible-playbook deploy.yml -l 172.16.10.101,172.16.10.102
Start the newly added node:
ansible-playbook start.yml -l 172.16.10.101,172.16.10.102
Update the Prometheus configuration and restart the cluster:
ansible-playbook rolling_update_monitor.yml --tags=prometheus
Monitor the status of the entire cluster and the newly added node by opening a browser to access the monitoring platform:
http://172.16.10.3:3000.
You can use the same procedure to add a TiKV node. But to add a PD node, some configuration files need to be manually updated.
Increase the capacity of a PD node
For example, if you want to add a PD node (node103) with the IP address 172.16.10.103, take the following steps:
Edit the
inventory.inifile and append the node information to the end of the[pd_servers]group:[tidb_servers] 172.16.10.4 172.16.10.5 [pd_servers] 172.16.10.1 172.16.10.2 172.16.10.3 172.16.10.103 [tikv_servers] 172.16.10.6 172.16.10.7 172.16.10.8 172.16.10.9 [monitored_servers] 172.16.10.4 172.16.10.5 172.16.10.1 172.16.10.2 172.16.10.3 172.16.10.103 172.16.10.6 172.16.10.7 172.16.10.8 172.16.10.9 [monitoring_servers] 172.16.10.3 [grafana_servers] 172.16.10.3Now the topology is as follows:
Name Host IP Services node1 172.16.10.1 PD1 node2 172.16.10.2 PD2 node3 172.16.10.3 PD3, Monitor node103 172.16.10.103 PD4 node4 172.16.10.4 TiDB1 node5 172.16.10.5 TiDB2 node6 172.16.10.6 TiKV1 node7 172.16.10.7 TiKV2 node8 172.16.10.8 TiKV3 node9 172.16.10.9 TiKV4 Initialize the newly added node:
ansible-playbook bootstrap.yml -l 172.16.10.103
Deploy the newly added node:
ansible-playbook deploy.yml -l 172.16.10.103
Login the newly added PD node and edit the starting script:
{deploy_dir}/scripts/run_pd.shRemove the
--initial-cluster="xxxx" \configuration.Note:
You cannot add the
#character at the beginning of the line. Otherwise, the following configuration cannot take effect.Add
--join="http://172.16.10.1:2379" \. The IP address (172.16.10.1) can be any of the existing PD IP address in the cluster.Manually start the PD service in the newly added PD node:
{deploy_dir}/scripts/start_pd.shUse
pd-ctlto check whether the new node is added successfully:./pd-ctl -u "http://172.16.10.1:2379"
Note:
pd-ctlis a command used to check the number of PD nodes.
Apply a rolling update to the entire cluster:
ansible-playbook rolling_update.yml
Start the monitor service:
ansible-playbook start.yml -l 172.16.10.103
Update the Prometheus configuration and restart the cluster:
ansible-playbook rolling_update_monitor.yml --tags=prometheus
Monitor the status of the entire cluster and the newly added node by opening a browser to access the monitoring platform:
http://172.16.10.3:3000.
Decrease the capacity of a TiDB node
For example, if you want to remove a TiDB node (node5) with the IP address 172.16.10.5, take the following steps:
Stop all services on node5:
ansible-playbook stop.yml -l 172.16.10.5
Edit the
inventory.inifile and remove the node information:[tidb_servers] 172.16.10.4 #172.16.10.5 # the removed node [pd_servers] 172.16.10.1 172.16.10.2 172.16.10.3 [tikv_servers] 172.16.10.6 172.16.10.7 172.16.10.8 172.16.10.9 [monitored_servers] 172.16.10.4 #172.16.10.5 # the removed node 172.16.10.1 172.16.10.2 172.16.10.3 172.16.10.6 172.16.10.7 172.16.10.8 172.16.10.9 [monitoring_servers] 172.16.10.3 [grafana_servers] 172.16.10.3Now the topology is as follows:
Name Host IP Services node1 172.16.10.1 PD1 node2 172.16.10.2 PD2 node3 172.16.10.3 PD3, Monitor node4 172.16.10.4 TiDB1 node5 172.16.10.5 TiDB2 removed node6 172.16.10.6 TiKV1 node7 172.16.10.7 TiKV2 node8 172.16.10.8 TiKV3 node9 172.16.10.9 TiKV4 Update the Prometheus configuration and restart the cluster:
ansible-playbook rolling_update_monitor.yml --tags=prometheus
Monitor the status of the entire cluster by opening a browser to access the monitoring platform:
http://172.16.10.3:3000.
Decrease the capacity of a TiKV node
For example, if you want to remove a TiKV node (node9) with the IP address 172.16.10.9, take the following steps:
Remove the node from the cluster using
pd-ctl:View the store ID of node9:
./pd-ctl -u "http://172.16.10.1:2379" -d store
Remove node9 from the cluster, assuming that the store ID is 10:
./pd-ctl -u "http://172.16.10.1:2379" -d store delete 10
Use
pd-ctlto check whether the node is successfully removed:./pd-ctl -u "http://172.16.10.1:2379" -d store 10
Note:
It takes some time to remove the node. If the status of the node you remove becomes Tombstone, then this node is successfully removed.
After the node is successfully removed, stop the services on node9:
ansible-playbook stop.yml -l 172.16.10.9
Edit the
inventory.inifile and remove the node information:[tidb_servers] 172.16.10.4 172.16.10.5 [pd_servers] 172.16.10.1 172.16.10.2 172.16.10.3 [tikv_servers] 172.16.10.6 172.16.10.7 172.16.10.8 #172.16.10.9 # the removed node [monitored_servers] 172.16.10.4 172.16.10.5 172.16.10.1 172.16.10.2 172.16.10.3 172.16.10.6 172.16.10.7 172.16.10.8 #172.16.10.9 # the removed node [monitoring_servers] 172.16.10.3 [grafana_servers] 172.16.10.3Now the topology is as follows:
Name Host IP Services node1 172.16.10.1 PD1 node2 172.16.10.2 PD2 node3 172.16.10.3 PD3, Monitor node4 172.16.10.4 TiDB1 node5 172.16.10.5 TiDB2 node6 172.16.10.6 TiKV1 node7 172.16.10.7 TiKV2 node8 172.16.10.8 TiKV3 node9 172.16.10.9 TiKV4 removed Update the Prometheus configuration and restart the cluster:
ansible-playbook rolling_update_monitor.yml --tags=prometheus
Monitor the status of the entire cluster by opening a browser to access the monitoring platform:
http://172.16.10.3:3000.
Decrease the capacity of a PD node
For example, if you want to remove a PD node (node2) with the IP address 172.16.10.2, take the following steps:
Remove the node from the cluster using
pd-ctl:View the name of node2:
./pd-ctl -u "http://172.16.10.1:2379" -d member
Remove node2 from the cluster, assuming that the name is pd2:
./pd-ctl -u "http://172.16.10.1:2379" -d member delete name pd2
Use Grafana or
pd-ctlto check whether the node is successfully removed:./pd-ctl -u "http://172.16.10.1:2379" -d member
After the node is successfully removed, stop the services on node2:
ansible-playbook stop.yml -l 172.16.10.2
Edit the
inventory.inifile and remove the node information:[tidb_servers] 172.16.10.4 172.16.10.5 [pd_servers] 172.16.10.1 #172.16.10.2 # the removed node 172.16.10.3 [tikv_servers] 172.16.10.6 172.16.10.7 172.16.10.8 172.16.10.9 [monitored_servers] 172.16.10.4 172.16.10.5 172.16.10.1 #172.16.10.2 # the removed node 172.16.10.3 172.16.10.6 172.16.10.7 172.16.10.8 172.16.10.9 [monitoring_servers] 172.16.10.3 [grafana_servers] 172.16.10.3Now the topology is as follows:
Name Host IP Services node1 172.16.10.1 PD1 node2 172.16.10.2 PD2 removed node3 172.16.10.3 PD3, Monitor node4 172.16.10.4 TiDB1 node5 172.16.10.5 TiDB2 node6 172.16.10.6 TiKV1 node7 172.16.10.7 TiKV2 node8 172.16.10.8 TiKV3 node9 172.16.10.9 TiKV4 Perform a rolling update to the entire TiDB cluster:
ansible-playbook rolling_update.yml
Update the Prometheus configuration and restart the cluster:
ansible-playbook rolling_update_monitor.yml --tags=prometheus
To monitor the status of the entire cluster, open a browser to access the monitoring platform:
http://172.16.10.3:3000.