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在 紧急故障转移 之后，ClusterSet 的不同部分之间的事务集存在差异的风险，您必须隔离集群以防止写入流量或所有流量。
如果发生网络分区，则可能会出现脑裂情况，即实例失去同步并且无法正确通信以定义同步状态。脑裂情况可能发生在以下情况下，例如当 DBA 决定强制选举副本集群成为主集群，从而创建多个主节点，导致脑裂情况。
在这种情况下，DBA 可以选择隔离原始主集群的
写入。
所有流量。
可以使用三种隔离操作
-
<Cluster>.fenceWrites(): 停止对 ClusterSet 主集群的写入流量。副本集群不接受写入，因此此操作对它们没有影响。可以在 INVALIDATED 副本集群上使用。此外，如果在禁用了
super_read_only的副本集群上运行，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()操作隔离写入流量的集群上运行。无法在副本集群上使用
cluster.unfenceWrites() -
<Cluster>.fenceAllTraffic(): 隔离集群及其中的所有读副本，禁止所有流量。如果您已使用<Cluster>.fenceAllTraffic()隔离了集群的所有流量，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，请参阅第 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)即使您主要在属于集群集的集群上使用隔离，也可以使用 <Cluster>.fenceAllTraffic() 隔离独立集群。
-
要隔离主集群的写入流量，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。集群中所有实例上的
super_read_only都已启用。所有应用程序都被阻止在集群上执行写入操作。
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 -
要检查您是否已隔离主集群的写入流量，请使用
<Cluster>.status命令，如下所示<Cluster>.clusterset.status()输出如下
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管理已启用，并且主集群实例上的super_read_only状态已启用。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 -
要隔离集群的所有流量，请使用 Cluster.fenceAllTraffic 命令，如下所示
<Cluster>.fenceAllTraffic()集群实例的主实例上的
super_read_only状态已启用。在启用集群中所有实例上的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 -
要解除隔离集群的所有流量，请使用
dba.rebootClusterFromCompleteOutage()MySQL Shell 命令。恢复集群后，当系统询问您是否要将实例重新加入集群时，选择是，即可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>