ORA-15112: No diskgroups are currently mounted
Cause: An ALTER DISKGROUP ALL command did not find any mounted diskgroups upon which to operate. Either instance shutdown or an ALTER DISKGROUP ALL DISMOUNT command did not dismount any diskgroups, or an ALTER DISKGROUP ALL UNDROP DISKS command did not undrop any disks.
Action: Mount the diskgroups on which you wish to operate or ignore the error.