My Oracle Support Banner

How to Mount the Diskgroup After Failure of Mount Force Command in Exadata (Doc ID 1398580.1)

Last updated on APRIL 12, 2022

Applies to:

Oracle Database - Enterprise Edition - Version to [Release 11.2]
Oracle Exadata Hardware - Version and later
Oracle Exadata Storage Server Software - Version and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Information in this document applies to any platform.


The diskgroup will be dismounted forcefully when both primary and mirror copy disk goes down/offline.

We cannot able to use mount force command to mount the diskgroup since both primary and mirror copies went down.

When there is any I/O failure happens on disk while writing,the disk will be taken offline immediately by ASM. If the disk can not be offlined since its other mirror copies are already offline (in case of high and normal redundancy diskgroup), then the diskgroup will be dismounted forcefully.

Now if you bring back the disk at OS side (cell side) which went offline first (ie taken offline by ASM first), still we will not be able to mount the diskgroup as the ASM updated the PST metadata with disk offline entry for that disk.

The PST will be updated only when the diskgroup is mounted at ASM.

Here we have dead-lock situation:  We cannot online the disk at ASM side which went offline as the diskgroup is not mounting it, and the diskgroup can not be mounted as both copies are down.

This document explains the method to recover from the above situation.

Troubleshooting Steps

To view full details, sign in with your My Oracle Support account.

Don't have a My Oracle Support account? Click to get started!

My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.