How to resolve the problem is in the link below:
Due to electrical maintenance work, a 2 node P4000 SAN cluster with failover manager, needed to be completely powered down, and this was done in the correct order – hosts accessing the SAN powered down first, then the SAN was shut down via the “Shut Down Management Group...” option in the HP StorageWorks P4000 Centralized Management Console (CMC).
Something went wrong when the SAN was powered back up, and the result was:
i: The Management Group was operating in Maintenance Mode.
ii: All the volumes (including the Network RAID tolerant volumes) had a status of 'Not Available'.
iii: One of the Storage Systems had a status of Failed