近期有个生产系统，计划做一套dr-autosync的集群，但是之前并没有这种类型系统的生产实施经验，就一点点的摸索，好在最后是顺利搭建成功了，把搭建过程分享出来给大家参考下。

1、集群架构

2、规划拓扑

根据集群架构规划拓扑文件

global:
  user: "tidb"
  ssh_port: 22
  deploy_dir: "/tidb/tidb-deploy"
  data_dir: "/tidb/tidb-data"
  arch: "arm64"

monitored:
  node_exporter_port: 19100
  blackbox_exporter_port: 19115

server_configs:
  tidb:
  tikv:   
  pd:
    dashboard.enable-telemetry: false
    log.file.max-backups: 100
    log.file.max-days: 90
    replication.isolation-level: logic
    replication.location-labels:
    
    - dc
    - logic
    - rack
    - host
    replication.max-replicas: 5
    schedule.max-store-down-time: 30m

pd_servers:
  - host: 10.3.65.1
    client_port: 12379
    peer_port: 12380
    
  - host: 10.3.65.2
    client_port: 12379
    peer_port: 12380
    
  - host: 10.3.65.3
    client_port: 12379
    peer_port: 12380

  - host: 10.3.65.1
    client_port: 12379
    peer_port: 12380

  - host: 10.3.65.2
    client_port: 12379
    peer_port: 12380

tidb_servers:
  - host: 10.3.65.1
    port: 24000
    status_port: 20080

  - host: 10.3.65.2
    port: 24000
    status_port: 20080

  - host: 10.3.65.3
    port: 24000
status_port: 20080

  - host: 10.3.65.1
    port: 24000
    status_port: 20080

  - host: 10.3.65.2
    port: 24000
    status_port: 20080

  - host: 10.3.65.3
    port: 24000
    status_port: 20080
                   
tikv_servers:
  - host: 10.3.65.1
    port: 20160
    status_port: 20180
    config:
      server.labels:
        dc: dc1
        logic: logic1
        rack: rack1
        host: host1

  - host: 10.3.65.2
    port: 20160
    status_port: 20180
    config:
      server.labels:
        dc: dc1
        logic: logic2
        rack: rack1
        host: host1

  - host: 10.3.65.3
    port: 20160
    status_port: 20180
    config:
      server.labels:
        dc: dc1
        logic: logic3
        rack: rack1
        host: host1

  - host: 10.3.65.1
    port: 20160
    status_port: 20180
    config:
      server.labels:
        dc: dc2
        logic: logic4
        rack: rack1
        host: host1        

  - host: 10.3.65.2
    port: 20160
    status_port: 20180
    config:
      server.labels:
        dc: dc2
        logic: logic5
        rack: rack1
        host: host1

  - host: 10.3.65.3
    port: 20160
    status_port: 20180
    config:
      server.labels:
        dc: dc2
        logic: logic6
        rack: rack1
        host: host1      

monitoring_servers:
  - host: 10.3.65.3
    port: 29090
    ng_port: 22020

grafana_servers:
  - host: 10.3.65.3
    port: 23000

alertmanager_servers:
  - host: 10.3.65.3
    web_port: 29093
    cluster_port: 29094

3、集群部署

1、部署集群

tiup cluster deploy dr-auto-sync v6.5.4 dr-auto-sync.yaml --user tidb -p

2、编写dr-auto-sync集群的json文件

vim rule.json

[
  {
    "group_id": "pd",
    "group_index": 0,
    "group_override": false,
    "rules": [
      {
        "group_id": "pd",
        "id": "dc1",
        "start_key": "",
        "end_key": "",
        "role": "voter",
        "count": 3,
        "location_labels": ["dc", "logic", "rack", "host"],
        "label_constraints": [{"key": "dc", "op": "in", "values": ["dc1"]}]
      },
      {
        "group_id": "pd",
        "id": "dc2",
        "start_key": "",
        "end_key": "",
        "role": "follower",
        "count": 2,
        "location_labels": ["dc", "logic", "rack", "host"],
        "label_constraints": [{"key": "dc", "op": "in", "values": ["dc2"]}]
      },
      {
        "group_id": "pd",
        "id": "dc2-1",
        "start_key": "",
        "end_key": "",
        "role": "learner",
        "count": 1,
        "location_labels": ["dc", "logic", "rack", "host"],
        "label_constraints": [{"key": "dc", "op": "in", "values": ["dc2"]}]
      }
    ]
  }
]

3、配置placement rule json文件，使其生效

[tidb@tidb141 ~]$ tiup ctl:v6.5.4 pd -u 10.3.65.141:22379 -i

» config placement-rules rule-bundle save --in="/home/tidb/rule.json"

检查配置是否生效

» config placement-rules show

4、修改dr-auto-sync 模式

config set replication-mode dr-auto-sync

5、配置dr-auto-sync 的机房标签

config set replication-mode dr-auto-sync label-key dc

6、配置主机房

config set replication-mode dr-auto-sync primary dc1

7、配置从机房

config set replication-mode dr-auto-sync dr dc2

8、配置主机房副本数量

config set replication-mode dr-auto-sync primary-replicas 3

9、配置从机房副本数量

config set replication-mode dr-auto-sync dr-replicas 2

10、如果集群为跨机房部署的dr-auto-sync 架构，需要确保pd leader 始终位于主机房，可以配置主机房pd权重高于备机房，数值越大权重越高，越优先考虑成为pd leader

tiup ctl:v6.5.3 pd –u 192.168.113.1:12379 -i
member leader_prioritypd-192.168.113.1-12379 100
member leader_prioritypd-192.168.113.2-12379 100
member leader_prioritypd-192.168.113.3-12379 100
member leader_prioritypd-192.168.113.4-12379 50
member leader_prioritypd-192.168.113.5-12379 50

11、检查集群同步状态

[tidb@tidb141 ~]$ curl http://10.3.65.141:22379/pd/api/v1/replication_mode/status

4、测试

1、手动关停备机房tikv节点，等待约一分钟左右，检查同步级别是否自动降级为async

[tidb@tidb141 ~]$ tiup cluster stop dr-auto-sync -N 10.3.65.142:10160,10.3.65.142:40160,10.3.65.142:50160

同步级别自动降级为async（异步）

2、启动关停的tikv节点，等待约一分钟左右，检查同步级别是否自动升级为sync

[tidb@tidb141 ~]$ tiup cluster start dr-auto-sync -N 10.3.65.142:10160,10.3.65.142:40160,10.3.65.142:50160

同步级别自动升级为sync，符合预期

至此，dr-auto-sync集群部署成功

5、总结

dr-auto-sync集群，较普通集群其实区别不大，只要按需规划好集群拓扑及、abels、json文件，基本上不会有什么问题，把它当作普通集群部署就可以，但有几点需要注意：

1、跨机房的话，需要配置pd的权重，防止pd leader跑到备机房，影响整体性能

2、我使用的6.5.4版本，dr-auto-sync有个bug，配置完成后，需要reload一下tikv节点，触发region leader重新选举，同步链路才会升级为sync状态，否则会一直卡在sync_recover阶段