VERITAS Volume Manager 3.1 Administrator's Guide

Introduction to Volume Manager
Volume Manager and RAID-5
Chapter 1 53
Figure 1-18 Incomplete Write
This failure case can be avoided by logging all data writes before
committing them to the array. In this way, the log can be replayed,
causing the data and parity updates to be completed before the
reconstruction of the failed drive takes place.
Logs are associated with a RAID-5 volume by being attached as
additional, non-RAID-5 layout plexes. More than one log plex can exist
for each RAID-5 volume, in which case the log areas are mirrored.
Disk A Disk B Disk C
Completed Data Write Corrupted Data Incomplete Parity Write