ORA-15130: diskgroup "string" is being dismounted

admin

ORA-15130: diskgroup"string"is being dismounted
Cause: The diskgroup is being dismounted by request orbecause an I/O error
was encountered that could not be handled by taking the disks offline. A disk
cannot be offlined whenever doing so could result in all copies of a redundant
extent being unavailable.
Action: Repairthe hardware problem and re-mount the diskgroup. Refer to the
alert log to determine which disks have failed.