对自管理副本集成员进行维护

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Overview
步骤

Overview

Replica sets allow a MongoDB deployment to remain available during the majority of a maintenance window.

This document outlines the basic procedure for performing maintenance on each of the members of a replica set. Furthermore, this particular sequence strives to minimize the amount of time that the 主节点 is unavailable and control the impact on the entire deployment.

Use these steps as the basis for common replica set operations, particularly for procedures such as upgrading to the latest version of MongoDB.

步骤

For each member of a replica set, starting with a secondary member, perform the following sequence of events, ending with the primary:

Restart the mongod instance as a standalone.
Perform the task on the standalone instance.
Restart the mongod instance as a member of the replica set.

Stop a secondary.

In mongosh, shut down the mongod instance:

db.shutdownServer()

Restart the secondary as a standalone on a different port.

At the operating system shell prompt restart mongod as a standalone instance.

如果使用配置文件，请进行以下配置更新：

注释掉 replication.replSetName 选项。
Change the net.port to a different port. Make a note of the original port setting as a comment.
在 setParameter 部分中将参数 disableLogicalSessionCacheRefresh 设置为 true。
If the mongod is a 分片 or config server member, you must also:
- 注释掉 sharding.clusterRole 选项。
- 在 setParameter 部分中将参数 skipShardingConfigurationChecks 设置为 true。

For example, if performing maintenance on a shard/config server replica set member for maintenance, the updated configuration file will include content like the following example:

net:
   bindIp: localhost,<hostname(s)|ip address(es)>
   port: 27218
#   port: 27018
#replication:
#   replSetName: shardA
#sharding:
#   clusterRole: shardsvr
setParameter:
   skipShardingConfigurationChecks: true
   disableLogicalSessionCacheRefresh: true

If using command-line options, make the following configuration updates to restart:

删除--replSetName 。
Modify --port to a different port.
Set parameter disableLogicalSessionCacheRefresh to true in the --setParameter option.
If the mongod is a 分片 or config server member, you must also:
- 如果是分片成员，则删除--shardsvr ；如果是配置服务器分片，则删除 { --configsvr 。
- Set parameter skipShardingConfigurationChecks to true in the setParameter section.

For example, to restart a replica set member that is not part of a sharded cluster:

mongod --port 27218 --dbpath /srv/mongodb --bind_ip localhost,<hostname(s)|ip address(es)> --setParameter disableLogicalSessionCacheRefresh=true

For example, to restart a shard/config server replica set member for maintenance:

mongod --port 27218 --dbpath /srv/mongodb --bind_ip localhost,<hostname(s)|ip address(es)> --setParameter skipShardingConfigurationChecks=true --setParameter disableLogicalSessionCacheRefresh=true

警告

将实例绑定到可公开访问的 IP 地址之前，必须保护集群免遭未经授权的访问。有关安全建议的完整列表，请参阅自管理部署的安全清单。至少应考虑启用身份验证和强化网络基础设施。

Always start mongod with the same user, even when restarting a replica set member as a standalone instance.

Perform maintenance operations on the secondary.

While the member is a standalone, use mongosh to perform maintenance:

mongo --port 27218

重要

While the member is a standalone, no writes are replicated to this member nor are writes on this member replicated to the other members of the replica set.

Ensure that any writes on this standalone do not conflict with oplog writes that will be applied to the member when it rejoins the replica set.

重新启动 `mongod` as a member of the replica set.

After performing all maintenance tasks, use the following procedure to restart the mongod as a member of the replica set on its usual port.

From mongosh, shut down the standalone server after completing the maintenance:

use admin
db.shutdownServer()

Restart the mongod instance as a replica set member with its original configuration; that is, undo the configuration changes made when starting as a standalone.

提示

请务必删除 disableLogicalSessionCacheRefresh 参数。

For shard or config server members, be sure to remove the skipShardingConfigurationChecks parameter.

When it has started, connect mongosh to the restarted instance.

The secondary takes time to catch up to the primary. From mongosh, use the following command to verify that the member has caught up from the RECOVERING state to the SECONDARY state.

rs.status()

Perform maintenance on the primary last.

To perform maintenance on the primary after completing maintenance tasks on all secondaries, connect mongosh to the primary and use rs.stepDown() to step down the primary and allow one of the secondaries to be elected the new primary. Specify a 300 second waiting period to prevent the member from being elected primary again for five minutes:
```
rs.stepDown(300)
```
After the primary steps down, the replica set will elect a new primary.
重新启动 mongod as a standalone instance, making the following configuration updates.