Veritas Volume Manager 5.0 Troubleshooting Guide Guide (September 2006)

29Recovery from hardware failure
Recovery from failure of a DCO volume
Recovering a version 0 DCO
For a version 0 DCO, perform the following steps to recover the DCO volume:
1 Correct the problem that caused the I/O failure.
2 Use the following command to remove the badlog flag from the DCO:
# vxdco [-g diskgroup] -o force enable dco_name
For the example output, the command would take this form:
# vxdco -g mydg -o force enable vol1_dco
The entry for vol1_dco in the output from vxprint now looks like this:
dc vol1_dco vol1 - - - -
3 Restart the DCO volume using the following command:
# vxvol [-g diskgroup] start dco_log_vol
For the example output, the command would take this form:
# vxvol -g mydg start vol1_dcl
4Use the vxassist snapclear command to clear the FastResync maps for the
original volume and for all its snapshots. This ensures that potentially stale
FastResync maps are not used when the snapshots are snapped back (a full
resynchronization is performed). FastResync tracking is re-enabled for any
subsequent snapshots of the volume.
Caution: You must use the vxassist snapclear command on all the snapshots of
the volume after removing the badlog flag from the DCO. Otherwise, data may be
lost or corrupted when the snapshots are snapped back.
If a volume and its snapshot volume are in the same disk group, the following
command clears the FastResync maps for both volumes:
# vxassist [-g diskgroup] snapclear volume \
snap_obj_to_snapshot
Here snap_obj_to_snapshot is the name of the snap object associated with volume
that points to the snapshot volume.
For the example output, the command would take this form:
# vxassist -g mydg snapclear vol1 SNAP-vol1_snp
If a snapshot volume and the original volume are in different disk groups, you must
perform a separate
snapclear operation on each volume:
# vxassist -g diskgroup1 snapclear volume snap_obj_to_snapshot
# vxassist -g diskgroup2 snapclear snapvol snap_obj_to_volume
Here snap_obj_to_volume is the name of the snap object associated with the
snapshot volume, snapvol, that points to the original volume.
For the example output, the commands would take this form if SNAP-vol1 had
been moved to the disk group, snapdg:
# vxassist -g mydg snapclear vol1 SNAP-vol1_snp
# vxassist -g snapdg snapclear SNAP-vol1 vol1_snp