If the root or /usr file system is defined on a mirrored volume, errors in the partition that underlies one of the mirrors can result in data corruption or system errors at boot time (when VxVM is started and assumes that the mirrors are synchronized).
The following workarounds exist for this situation:
Mount one plex of the root or /usr file system, repair it, unmount it, and use dd to copy the fixed plex to all other plexes. This procedure is not recommended as it can be error prone.
Restore the system from a valid backup. This procedure does not require the operating system to be re-installed from the base CD-ROM. It provides a simple, efficient, and reliable means of recovery when both the root disk and its mirror are damaged.