Dell EMC Metro node 7.0.1 Online Help

Rule sets are predefined rules that determine which cluster continues I/O during an inter-cluster link failure or cluster failure. In these situations, until communication is restored, most I/O workloads require specific sets of virtual volumes to resume on one cluster and remain suspended on the other cluster.

In a metro node Metro configuration, there is a Management Console on the management server in each cluster. You can create distributed devices by using the GUI or CLI on either management server. During communication problems, the default rule set makes the cluster that is used to create the distributed device the winner cluster. I/O proceeds on the winner cluster and is suspended on the loser cluster. The following table describes how I/O proceeds when you use the default rule sets:

You can change a distributed device's default rule set in the Distributed Device Properties dialog box if the distributed device is not in a consistency group. The CLI Guide for metro node provides detailed information about creating and managing rule sets.