tidb 扩容和缩容

tidb的官方给出了单台机器的硬盘上限最多2T，量大的很快就会满，扩容就很重要。

1，扩容前的准备工作

参考：tidb 集群安装配置

因没有给tidb免密获取root权限导致以下错误

Error: Failed to initialize TiDB environment on remote host '10.0.54.6' (task.env_init.failed)
caused by: Failed to create '~/.ssh' directory for user 'tidb'

2，以扩容tikv为例

$ cat add-tikv.yaml
tikv_servers:
  - host: 10.0.54.6

3，查看集群信息

# tiup cluster list   //查看集群列表
# tiup cluster display test_tidb //查看某一集群详细信息

4，扩容tikv

[tidb@testjian conf]$ tiup cluster scale-out test_tidb add-tikv.yaml
Found cluster newer version:

    The latest version:         v1.5.6
    Local installed version:    v1.5.3
    Update current component:   tiup update cluster
    Update all components:      tiup update --all

Starting component `cluster`: /home/tidb/.tiup/components/cluster/v1.5.3/tiup-cluster scale-out test_tidb add-tikv.yaml
Please confirm your topology:
Cluster type:    tidb
Cluster name:    test_tidb
Cluster version: v4.0.8
Role  Host       Ports        OS/Arch       Directories
----  ----       -----        -------       -----------
tikv  10.0.54.6  20160/20180  linux/x86_64  /home/tidb/tidb-deploy/tikv-20160,/home/tidb/tidb-data/tikv-20160
Attention:
    1. If the topology is not what you expected, check your yaml file.
    2. Please confirm there is no port/directory conflicts in same host.
Do you want to continue? [y/N]: (default=N) y
+ [ Serial ] - SSHKeySet: privateKey=/home/tidb/.tiup/storage/cluster/clusters/test_tidb/ssh/id_rsa, publicKey=/home/tidb/.tiup/storage/cluster/clusters/test_tidb/ssh/id_rsa.pub
==================================省略==============================
+ [ Serial ] - SystemCtl: host=10.0.10.23 action=reload prometheus-9090.service
+ [ Serial ] - UpdateTopology: cluster=test_tidb
Scaled cluster `test_tidb` out successfully

[tidb@testjian conf]$ tiup cluster display test_tidb  //查看是否添加成功

新增的tikv，不会立马进行数据平衡，但是数据的增加会更加倾向于新增的机器。

扩容tikv

5，缩容

[tidb@testjian conf]$ tiup cluster scale-in test_tidb --node 10.0.54.17:4000 --force
Found cluster newer version:

    The latest version:         v1.5.6
    Local installed version:    v1.5.3
    Update current component:   tiup update cluster
    Update all components:      tiup update --all

Starting component `cluster`: /home/tidb/.tiup/components/cluster/v1.5.3/tiup-cluster scale-in test_tidb --node 10.0.54.17:4000 --force
Forcing scale in is unsafe and may result in data loss for stateful components.
The process is irreversible and could NOT be cancelled.
Only use `--force` when some of the servers are already permanently offline.
Are you sure to continue? [y/N]:(default=N) y
This operation will delete the 10.0.54.17:4000 nodes in `test_tidb` and all their data.
Do you want to continue? [y/N]:(default=N) y
Scale-in nodes...
+ [ Serial ] - SSHKeySet: privateKey=/home/tidb/.tiup/storage/cluster/clusters/test_tidb/ssh/id_rsa, publicKey=/home/tidb/.tiup/storage/cluster/clusters/test_tidb/ssh/id_rsa.pub
+ [Parallel] - UserSSH: user=tidb, host=10.0.10.23
+ [Parallel] - UserSSH: user=tidb, host=10.0.55.16
+ [Parallel] - UserSSH: user=tidb, host=10.0.55.16
+ [Parallel] - UserSSH: user=tidb, host=10.0.10.23
+ [Parallel] - UserSSH: user=tidb, host=10.0.55.17

==================================省略==============================

--force慎用，特别是tikv,tiflash。