Cluster I/O Fencing – exclusion strategy

가끔 RAC나 CRS 관련해 문서를 보다보면 I/O fencing이라는 말이 나오는데, 이게 무슨 말일까요?

다음은 Cluster I/O fencing에 대한 설명입니다.

There will be some situations where the leftover write operations from failed database instances reach the storage system after the recovery process starts, such as when the cluster function failed on the nodes, but the nodes are still running at OS level.

Since these write operations are no longer in the proper serial order, they can damage the consistency of the stored data. Therefore, when a cluster node fails, the failed node needs to be fenced off from all the shared disk devices or disk groups.

This methodology is called I/O Fencing, sometimes called Disk Fencing or failure fencing.

정리해 보자면, cluster 구성에서 떨어져 나간 노드의 I/O를 방지하는 방법?