Scenario:
The Cluster Volume Manager (CVM) Master node fails and the role is switched to a secondary node. The Disk Group goes into disabled state and is unable to be deported. After starting all the volumes in order to bring the Disk Group online, attempts to deport still fail.

Error Message:
# umount -f /opt/app/oracle
UX:vxfs umount: ERROR: V-3-26360: file system /opt/app/oracle has been mount locked

Run the following command to check for VCS lock:
# mount -v | grep [disk_group]
/dev/vx/dsk/DG/Volume - /MountPoint vxfs - no rw,suid,delaylog,largefiles,qio,cluster,ioerror=mdisable,crw,mntlock=VCS,xattr


Cause
There is still a VCS lock on mount point for the volume, even though df -h does not show the mount online.


Solution
How to check if the filesystem is locked by VCS:

# mount -v | grep mntlock

Sometimes, it may be necessary to unmount a mount locked filesystem. This is for cases where VCS service groups having DiskGroup resources configured with UnMountVolumes attribute set and the volumes are mounted outside of VCS control (this is not very common). Use the VxFS umount command for Solaris and vxumount command for Linux to manually unmount the file system

Solaris:
# /opt/VRTS/bin/umount -o mntunlock=VCS </mount-point>

Linux:
# /usr/lib/fs/vxfs/vxumount -o mntunlock=VCS </mount-point>

Example:
# mount -v | grep mntlock
/dev/vx/dsk/oracledg/oracle on /opt/app/oracle type vxfs read/write/setuid/devices/mincache=direct/convosync=direct/delaylog/largefiles/qio/ioerror=mwdisable/mntlock=VCS/dev=46c2ee0 on Mon Sep 15 18:28:18 2008
# /opt/VRTS/bin/umount -o mntunlock=VCS /opt/app/oracle