VERITAS Volume Manager 3.5 Administrator's Guide (September 2004)

Creating and Administering Plexes
Displaying Plex Information
Chapter 6196
• determine if a plex contains a valid copy (mirror) of the volume
contents
• track whether a plex was in active use at the time of a system failure
• monitor operations on plexes
This section explains the individual plex states in detail. For more
information about the possible transitions between plex states and how
these are applied during volume recovery, see the chapter
“Understanding the Plex State Cycle” in the section “Recovery from
Hardware Failure” in the VERITAS Volume Manager Troubleshooting
Guide.
Plexes that are associated with a volume have one of the following states:
ACTIVE Plex State
A plex can be in the ACTIVE state in two ways:
• when the volume is started and the plex fully participates in normal
volume I/O (the plex contents change as the contents of the volume
change)
• when the volume is stopped as a result of a system crash and the
plex is ACTIVE at the moment of the crash
In the latter case, a system failure can leave plex contents in an
inconsistent state. When a volume is started, VxVM does the recovery
action to guarantee that the contents of the plexes marked as ACTIVE
are made identical.
NOTE On a system running well, ACTIVE should be the most common state
you see for any volume plexes.
CLEAN Plex State
A plex is in a CLEAN state when it is known to contain a consistent copy
(mirror) of the volume contents and an operation has disabled the
volume. As a result, when all plexes of a volume are clean, no action is
required to guarantee that the plexes are identical when that volume is
started.