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在 紧急故障转移 后，如果 ClusterSet 的各个部分之间存在事务集不同的风险，则必须隔离集群，使其无法进行写入操作，或使其无法进行任何操作。
如果发生网络分区，则可能出现脑裂情况，在这种情况下，实例会失去同步，并且无法正常通信来确定同步状态。脑裂可能发生在以下情况：DBA 决定强制选择一个副本集群成为主集群，从而创建多个主集群，从而导致脑裂情况。
在这种情况下，DBA 可以选择从以下方面隔离原始主集群：
写入。
所有流量。
提供三种隔离操作
-
<Cluster>.fenceWrites(): 停止对 ClusterSet 的主集群的写入流量。副本集群不接受写入操作，因此此操作对它们没有影响。可以对无效的副本集群使用。此外，如果针对禁用
super_read_only的副本集群运行，它将启用它。 -
<Cluster>.unfenceWrites(): 恢复写入流量。此操作可以在之前使用<Cluster>.fenceWrites()操作从写入流量中隔离的集群上运行。无法对副本集群使用
cluster.unfenceWrites() -
<Cluster>.fenceAllTraffic(): 隔离集群及其中的所有只读副本，使其无法进行任何操作。如果使用<Cluster>.fenceAllTraffic()从所有流量中隔离了集群，则必须使用dba.rebootClusterFromCompleteOutage()MySQL Shell 命令重新启动集群。有关
dba.rebootClusterFromCompleteOutage()的更多信息，请参见 第 7.8.3 节“从重大故障中重新启动集群”。
fenceWrites()
在副本集群上发出 .fenceWrites() 会返回错误
ERROR: Unable to fence Cluster from write traffic:
operation not permitted on REPLICA Clusters
Cluster.fenceWrites: The Cluster '<Cluster>' is a REPLICA Cluster
of the ClusterSet '<ClusterSet>' (MYSQLSH 51616)虽然主要在属于集群集的集群上使用隔离，但也可以使用 <Cluster>.fenceAllTraffic() 隔离独立集群。
-
要从写入流量中隔离主集群，请使用 Cluster.fenceWrites 命令，如下所示
<Cluster>.fenceWrites()运行命令后
集群上的自动
super_read_only管理被禁用。super_read_only在集群中的所有实例上启用。所有应用程序都被阻止对集群执行写入操作。
cluster.fenceWrites() The Cluster 'primary' will be fenced from write traffic * Disabling automatic super_read_only management on the Cluster... * Enabling super_read_only on '127.0.0.1:3311'... * Enabling super_read_only on '127.0.0.1:3312'... * Enabling super_read_only on '127.0.0.1:3313'... NOTE: Applications will now be blocked from performing writes on Cluster 'primary'. Use <Cluster>.unfenceWrites() to resume writes if you are certain a split-brain is not in effect. Cluster successfully fenced from write traffic -
要检查是否已从写入流量中隔离主集群，请使用
<Cluster>.status命令，如下所示<Cluster>.clusterset.status()输出如下所示
clusterset.status() { "clusters": { "primary": { "clusterErrors": [ "WARNING: Cluster is fenced from Write traffic. Use cluster.unfenceWrites() to unfence the Cluster." ], "clusterRole": "PRIMARY", "globalStatus": "OK_FENCED_WRITES", "primary": null, "status": "FENCED_WRITES", "statusText": "Cluster is fenced from Write Traffic." }, "replica": { "clusterRole": "REPLICA", "clusterSetReplicationStatus": "OK", "globalStatus": "OK" } }, "domainName": "primary", "globalPrimaryInstance": null, "primaryCluster": "primary", "status": "UNAVAILABLE", "statusText": "Primary Cluster is fenced from write traffic." -
要解除隔离集群并恢复对主集群的写入流量，请使用 Cluster.fenceWrites 命令，如下所示
<Cluster>.unfenceWrites()主集群上的自动
super_read_only管理被启用，并且主集群实例上的super_read_only状态被启用。cluster.unfenceWrites() The Cluster 'primary' will be unfenced from write traffic * Enabling automatic super_read_only management on the Cluster... * Disabling super_read_only on the primary '127.0.0.1:3311'... Cluster successfully unfenced from write traffic -
要从所有流量中隔离集群，请使用 Cluster.fenceAllTraffic 命令，如下所示
<Cluster>.fenceAllTraffic()集群实例的主实例上启用了
super_read_only状态。在所有集群实例上启用offline_mode之前cluster.fenceAllTraffic() The Cluster 'primary' will be fenced from all traffic * Enabling super_read_only on the primary '127.0.0.1:3311'... * Enabling offline_mode on the primary '127.0.0.1:3311'... * Enabling offline_mode on '127.0.0.1:3312'... * Stopping Group Replication on '127.0.0.1:3312'... * Enabling offline_mode on '127.0.0.1:3313'... * Stopping Group Replication on '127.0.0.1:3313'... * Stopping Group Replication on the primary '127.0.0.1:3311'... Cluster successfully fenced from all traffic -
要解除隔离集群，使其可以进行所有操作，请使用
dba.rebootClusterFromCompleteOutage()MySQL Shell 命令。当您恢复集群后，通过在询问是否要将实例重新加入集群时选择 Y 来将实例重新加入集群cluster = dba.rebootClusterFromCompleteOutage() Restoring the cluster 'primary' from complete outage... The instance '127.0.0.1:3312' was part of the cluster configuration. Would you like to rejoin it to the cluster? [y/N]: Y The instance '127.0.0.1:3313' was part of the cluster configuration. Would you like to rejoin it to the cluster? [y/N]: Y * Waiting for seed instance to become ONLINE... 127.0.0.1:3311 was restored. Rejoining '127.0.0.1:3312' to the cluster. Rejoining instance '127.0.0.1:3312' to cluster 'primary'... The instance '127.0.0.1:3312' was successfully rejoined to the cluster. Rejoining '127.0.0.1:3313' to the cluster. Rejoining instance '127.0.0.1:3313' to cluster 'primary'... The instance '127.0.0.1:3313' was successfully rejoined to the cluster. The cluster was successfully rebooted. <Cluster:primary>