VERITAS Volume Manager 4.1 Troubleshooting Guide

Recovery from Hardware Failure

Recovering a Version 0 DCO

Chapter 1 31

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

4. Use the vxassistsnapclear 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 vxassistsnapclear 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