replSetReconfig

Global Write Concern全局写入问题

Starting in MongoDB 5.0, you must explicitly set the global default write concern before attempting to reconfigure a replica set with a configuration that would change the implicit default write concern. 从MongoDB 5.0开始，您必须先显式设置全局默认写入关注，然后再尝试使用更改隐式默认写问题的配置重新配置副本集。To set the global default write concern, use the setDefaultRWConcern command.要设置全局默认写入关注点，请使用setDefaultRWConcern命令。

term Replica Configuration Field复制副本配置字段

MongoDB 4.4 adds the term field to the replica set configuration document. MongoDB 4.4将term字段添加到副本集配置文档中。The term field is set by the primary replica set member. term字段由primary副本集成员设置。The primary ignores the term field if set explicitly in the replSetReconfig operation.如果在replSetReconfig操作中显式设置，则primary将忽略term字段。

Reconfiguration Can Add or Remove No More than One Voting Member at a Time重新配置一次最多可以添加或删除一个投票成员

Starting in MongoDB 4.4, replSetReconfig by default allows adding or removing no more than 1 voting member at a time. 从MongoDB 4.4开始，replSetReconfig默认允许一次添加或删除不超过1个voting成员。For example, a new configuration can make at most one of the following changes to the cluster membership:例如，新配置最多可以对群集membership进行以下更改之一：

• Adding a new voting replica set member.添加新的投票副本集成员。
• Removing an existing voting replica set member.正在删除现有投票副本集成员。
• Modifying the votes for an existing replica set member.修改现有副本集成员的votes。

To add or remove multiple voting members, issue a series of replSetReconfig operations to add or remove one member at a time.要添加或删除多个投票成员，请执行一系列replSetReconfig操作，一次添加或删除一个成员。

Issuing a force reconfiguration immediately installs the new configuration even if it adds or removes multiple voting members. 即使添加或删除多个投票成员，发布强制重新配置也会立即安装新配置。Force reconfiguration can cause unexpected behavior, such as the rollback of "majority" committed write operations.强制重新配置可能会导致意外行为，例如回滚"majority"提交的写入操作。

Reconfiguration Waits Until a Majority of Members Install the Replica Configuration重新配置等待大多数成员安装副本配置

Starting in MongoDB 4.4, replSetReconfig waits until a majority of voting replica set members install the new replica configuration before returning success. 从MongoDB 4.4开始，replSetReconfig等待大多数投票副本集成员安装新的副本配置，然后返回成功。A voting member is any replica set member where members[n].votes is 1, including arbiters.投票成员是members[n].votes为1的任何复制集成员，包括仲裁员。

Replica set members propagate their replica configuration via heartbeats. 副本集成员通过心跳传播其副本配置。Whenever a member learns of a configuration with a higher version and term, it installs the new configuration. 每当成员了解到具有更高version和term的配置时，就会安装新配置。The reconfiguration process has two distinct 'waiting' phases:重新配置过程有两个不同的“等待”阶段：

1) Wait for the current configuration to be committed before installing the new configuration.在安装新配置之前，请等待提交当前配置。

The "current" configuration refers to the replica configuration in use by the primary at the time replSetReconfig is issued.“当前”配置是指发出replSetReconfig时主服务器正在使用的副本配置。

A configuration is committed when:在以下情况下提交配置：

• A majority of voting replica set members have installed the current configuration, and大多数投票副本集成员已安装当前配置，并且
• All writes which were "majority" committed in the previous configuration have also replicated to a majority in the current configuration.在前一配置中提交的所有"majority"写入也已复制到当前配置中的多数。

Typically, the current configuration has already been installed on a majority of voting replica set members. 通常，当前配置已安装在大多数投票副本集成员上。However, the majority committed writes in the previous configuration may not all be committed in the current configuration. 但是，在以前的配置中提交的大多数写入可能不会全部在当前配置中提交。Delayed members or members that are lagging behind the primary can increase the time spent in this phase.延迟的成员或落后于primary的成员可能会增加此阶段所花费的时间。

If the operation was issued with a maxTimeMS limit andthe operation exceeds the limit while waiting, the operation returns an error and discard the new configuration. 如果发出的操作具有maxTimeMS限制，并且在等待时操作超过了限制，则操作将返回错误并放弃新配置。The limit is cumulative and does not reset after proceeding to the next phase.该限制是累积的，在进入下一阶段后不会重置。

2) Wait for a majority of voting members in the new configuration to install the new configuration.等待新配置中的大多数投票成员安装新配置。

The "new" configuration refers to the replica configuration specified to replSetReconfig.“新”配置是指为replSetReconfig指定的副本配置。

The primary installs and begins using the new replica configuration before propagating the configuration to the remaining replica set members. 主服务器安装并开始使用新的复制副本配置，然后将配置传播到其余的复制副本集成员。The operation only waits for a majority of voting members to install the new configuration, and does not require waiting for the new configuration to be committed.该操作仅等待大多数投票成员安装新配置，而不需要等待提交新配置。

If the operation was issued with a maxTimeMS limit and the operation exceeds the limit while waiting, the operation returns an error but continues using and propagating the new configuration.如果发出的操作具有maxTimeMS限制，并且在等待时操作超过了限制，则操作将返回错误，但会继续使用并传播新配置。

Issuing a force reconfiguration immediately installs the new configuration regardless of the commitment status of the previous configuration. 无论先前配置的承诺状态如何，发布强制重新配置都会立即安装新配置。Force reconfiguration can cause unexpected behavior, such as the rollback of "majority" committed write operations.强制重新配置可能会导致意外行为，例如回滚"majority"提交的写入操作。

To check the commitment status of the current replica configuration, issue replSetGetConfig with the commitmentStatus parameter on the replica set primary.要检查当前副本配置的承诺状态，请在副本集primary上发出带有commitmentStatus参数的replSetGetConfig。

Automatic Reconfiguration for New Voting Replica Set Members新投票副本集成员的自动重新配置

Starting in MongoDB 5.0, a newly added secondary does not count as a voting member and cannot be elected until it has reached the SECONDARY state.从MongoDB 5.0开始，新添加的次要成员不算作投票成员，在达到SECONDARY状态之前不能当选。

When a new voting node is added to a replica set, replSetReconfig will internally add a newlyAdded field to the node's configuration. 当新的投票节点添加到副本集时，replSetReconfig将在内部向节点的配置中添加一个newAdded字段。Nodes with the newlyAdded field do not count towards the current number of voting nodes. 具有newAdded字段的节点不计入当前投票节点数。When initial sync completes and the node reaches SECONDARY state, the newlyAdded field is automatically removed.当初始同步完成并且节点达到SECONDARY状态时，newlyAdded字段将自动删除。

Access Control访问控制

To run the command on deployments that enforce access control, the user must have replSetConfigure privilege action on the cluster resource. 若要在实施访问控制的部署上运行该命令，用户必须对群集资源具有replSetConfigure权限操作。The clusterManager built-in role, available in the admin database, provides the required privileges for this command.admin数据库中提供的clusterManager内置角色为该命令提供了所需的权限。

Locking Behavior锁定行为

replSetReconfig obtains a special mutually exclusive lock to prevent more than one replSetReconfig operation from occurring at the same time.获取一个特殊的互斥锁，以防止同时发生多个replSetReconfig操作。

Mixed Version Replica Set混合版本副本集

Availability可用性

A majority of the set's members must be operational for the changes to propagate properly.集合的大多数成员必须是可操作的，才能正确传播更改。

replSetReconfig can trigger the current primary to step down in some situations. 在某些情况下，可能会触发当前的主设备降级。Primary step-down triggers an election to select a new primary:初选递降会触发选择新primary的选举：

• Starting in MongoDB 4.4, when the new primary steps up, it increments the term field to distinguish configuration changes made on the new primary from changes made on the previous primary.从MongoDB 4.4开始，当新的主服务器升级时，它会增加term字段，以区分在新主服务器上所做的配置更改与在上一个主服务器上进行的更改。
• Starting in MongoDB 4.2, when the primary steps down, it no longer closes all client connections; however, writes that were in progress are killed. 从MongoDB 4.2开始，当主服务器关闭时，它不再关闭所有客户端连接；然而，正在进行的写作被扼杀。For details, see Behavior.有关详细信息，请参阅行为。
• In MongoDB 4.0 and earlier, when the primary steps down, it closes all client connections.在MongoDB 4.0及更早版本中，当主服务器关闭时，它会关闭所有客户端连接。

The median time before a cluster elects a new primary should not typically exceed 12 seconds, assuming default replica configuration settings. 假设默认副本配置设置，群集选择新主服务器之前的中值时间通常不应超过12秒。This includes time required to mark the primary as unavailable and call and complete an election. 这包括将初选标记为不可用、致电并完成选举所需的时间。You can tune this time period by modifying the settings.electionTimeoutMillis replication configuration option. 您可以通过修改settings.electionTimeoutMillis复制配置选项来调整此时间段。Factors such as network latency may extend the time required for replica set elections to complete, which in turn affects the amount of time your cluster may operate without a primary. 网络延迟等因素可能会延长副本集选择完成所需的时间，进而影响集群在没有主节点的情况下运行的时间。These factors are dependent on your particular cluster architecture.这些因素取决于您的特定集群体系结构。

During the election process, the cluster cannot accept write operations until it elects the new primary.在选择过程中，群集在选择新的主节点之前无法接受写操作。

Your application connection logic should include tolerance for automatic failovers and the subsequent elections. 应用程序连接逻辑应包括对自动故障切换和后续选择的容忍度。Starting in MongoDB 3.6, MongoDB drivers can detect the loss of the primary and automatically retry certain write operations a single time, providing additional built-in handling of automatic failovers and elections:从MongoDB 3.6开始，MongoDB驱动程序可以检测主设备的丢失，并在一次自动重试某些写入操作，从而提供自动故障切换和选择的额外内置处理：

• MongoDB 4.2+ compatible drivers enable retryable writes by defaultMongoDB 4.2+兼容驱动程序默认启用可重试写入
• MongoDB 4.0 and 3.6-compatible drivers must explicitly enable retryable writes by including retryWrites=true in the connection string.MongoDB 4.0和3.6兼容的驱动程序必须通过在连接字符串中包含retryWrites=true来显式启用可重试写入。

To further reduce potential impact to a production cluster, reconfigure only during scheduled maintenance periods.为了进一步减少对生产集群的潜在影响，请仅在计划的维护期间重新配置。

{ force: true }

Drop Outgoing Connections After Removing a Member删除成员后删除传出连接

Using replSetReconfig to remove a replica set member does not automatically drop open outgoing connections from other replica set members to the removed member.使用replSetReconfig删除副本集成员不会自动删除从其他副本集成员到已删除成员的打开传出连接。

By default, replica set members wait for 5 minutes before dropping connections to the removed member. 默认情况下，副本集成员在断开与已删除成员的连接之前等待5分钟。In sharded replica sets, you can modify this timeout using the ShardingTaskExecutorPoolHostTimeoutMS server parameter.在分片副本集中，可以使用ShardingTaskExecutorPoolHostTimeoutMS服务器参数修改此超时。

db.adminCommand(
  {
    "dropConnections" : 1,
    "hostAndPort" : [
      "<hostname>:<port>"
    ]
  }
)

Replace <hostname> and <port> with those of the removed member.将<hostname>和<port>替换为已删除成员的名称。

Member Priority and Votes成员优先级和投票

• Members with priority greater than 0 cannot have 0 votes.priority大于0的成员不能有0votes。
• Non-voting (i.e. votes is 0) members must have priority of 0.无表决权（即votes为0）成员的priority必须为0。