在 紧急故障转移之后，并且存在事务集在 ClusterSet 的各个部分之间不同的风险，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，其中实例失去同步并且无法正确通信以定义同步状态。当 DBA 决定强行选择一个副本集群成为主集群创建多个主节点时，可能会发生裂脑，从而导致裂脑情况。
在这种情况下，DBA 可以选择隔离原始主集群：
写。
所有流量。
可以使用三种防护操作：
-
<Cluster>.fenceWrites()：停止向 ClusterSet 的主集群写入流量。副本集群不接受写入，所以这个操作对它们没有影响。从 8.0.31 开始，可以在 INVALIDATED 副本集群上使用。此外，如果针对
super_read_only禁用的副本集群运行，它将启用它。 -
<Cluster>.unfenceWrites()：恢复写入流量。此操作可以在先前使用该<Cluster>.fenceWrites()操作隔离写入流量的集群上运行。无法
cluster.unfenceWrites() -
<Cluster>.fenceAllTraffic()：隔离所有流量的集群。如果您使用 隔离了集群的所有流量 ，则必须使用 MySQL Shell 命令<Cluster>.fenceAllTraffic()重新启动集群 。dba.rebootClusterFromCompleteOutage()有关更多信息
dba.rebootClusterFromCompleteOutage()，请参阅第 7.8.3 节，“从主要中断中重启集群”。
在副本集群.fenceWrites()上发布会返回错误：
Press CTRL+C to copyERROR: 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防护，也可以使用<Cluster>.fenceAllTraffic().
-
要隔离主集群的写入流量，请使用 Cluster.fenceWrites 命令，如下所示：
Press CTRL+C to copy<Cluster>.fenceWrites()运行命令后：
super_read_only集群上 的自动管理被禁用。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在集群上执行写入。
Press CTRL+C to copycluster.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 -
要检查您是否已将主集群隔离在写入流量之外，请使用以下
<Cluster>.status命令：Press CTRL+C to copy<Cluster>.clusterset.status()输出如下：
Press CTRL+C to copyclusterset.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." -
要取消对集群的防护并恢复对主集群的写入流量，请使用 Cluster.fenceWrites 命令，如下所示：
Press CTRL+C to copy<Cluster>.unfenceWrites()主集群自动
super_read_only管理开启，super_read_only主集群实例状态。Press CTRL+C to copycluster.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 -
要隔离集群中的所有流量，请使用 Cluster.fenceAllTraffic 命令，如下所示：
Press CTRL+C to copy<Cluster>.fenceAllTraffic()状态在集群实例的
super_read_only主实例上启用。offline_mode在集群中的所有实例上 启用之前 ：Press CTRL+C to copycluster.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 -
要从所有流量中取消对集群的防护，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，您可以通过选择 Y将实例重新加入集群：Press CTRL+C to copycluster = 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>