Dell EMC Metro node 7.1 Administrator Guide

Marking a Back-End IT Nexus Isolated due to Unstable Performance

If a back-end IT path is found to cycle between degraded and undegraded three times within a 30 minute period, then the IT Nexus is considered unstable and the metro node automatically stops using the IT Nexus for host-based I/O. In this state, the VPlexcli command back-end degraded list list the Degradation Reason as Isolated due to unstable performance.

In this case, the IT Nexus remains degraded until the user manually restores it using the VPlexcli command back-end degraded recover. It is also possible that threshold reaches to its four-hour default value, after which the IT nexus is marked as performance degraded while the recovery process checks its health before undegrading it (and automatically re-enabling the path to serve host-based I/O again if the performance tests pass). If the intermittent latency issue is continued on the IT Nexus and the user is unable to address the root cause, then it is advised to engage metro node Customer Service to manually mark the IT Nexus degraded to remove the path from use until the underlying issue is resolved.