If a disk failure caused a volume to be disabled, and the volume does not contain any valid redundant plexes, you must restore the volume from a backup after replacing the failed disk. Any volumes that are listed as Unstartable must be restarted using the vxvol command before restoring their contents from a backup.
To forcibly restart a disabled volume
# vxvol [-g diskgroup] -o bg -f start volume
The -f option forcibly restarts the volume, and the -o bg option resynchronizes its plexes as a background task. For example, to restart the volume myvol so that it can be restored from backup, use the following command:
# vxvol -g mydg -o bg -f start myvol