You must actively track whether LUNs are online or offline in a MetroCluster configuration. If the cf.takeover.change_fsid option is set to on, and there is a disaster, all LUNs in the aggregates that were mirrored at the surviving site are offline. You can’t determine if they were online prior to the disaster unless you track their state.
If you have a MetroCluster configuration, you must actively track the state of LUNs (track whether they are online or offline) on the node at each site. If there is a failure to a MetroCluster configuration that qualifies as a disaster and the node at one site is inaccessible, all LUNs in the aggregates that were mirrored at the surviving site are offline. There is no way to distinguish the LUNs that were offline before the disaster from the LUNs that were online before the disaster unless you have been tracking their status.
When you recover access to the failed node’s LUNs, it is important to bring back online only the LUNs that were online before the disaster. To avoid igroup mapping conflicts, do not bring a LUN online if it was offline before the disaster. For example, suppose you have two LUNs with IDs of 5 mapped to the same igroup, but one of these LUNs was offline before the disaster. If you bring the previously offline LUN online first, you cannot bring the second LUN online because you cannot have two LUNs with the same ID mapped to the same host.