VERITAS Volume Manager 3.5 Administrator's Guide (September 2002)

Glossary 319
persistent state logging
A logging type that ensures that only active mirrors are used for recovery purposes and
prevents failed mirrors from being selected for recovery. This is also known as kernel
logging.
physical disk
The underlying storage device, which may or may not be under VxVM control.
plex
A plex is a logical grouping of subdisks that creates an area of disk space independent of
physical disk sizeor other restrictions. Mirroring is setup by creating multiple dataplexes
for asingle volume. Eachdata plex in a mirrored volume contains anidentical copy ofthe
volume data. Plexes may also be created to represent concatenated, striped and RAID-5
volume layouts, and to store volume logs.
primary path
In active/passive disk arrays, a disk can be bound to one particular controller on the disk
array or owned by a controller. The disk can then be accessed using the path through this
particular controller. Also see path and secondary path.
private disk group
A disk group in which the disks are accessed by only one specific host in a cluster. Also
see shared disk group.
private region
A region of a physical disk used to store private, structured VxVM information. The
private regioncontains adisk header, atable ofcontents, anda configurationdatabase. The
table of contents maps the contents of the disk. The disk header contains a disk ID. All
data in the private region is duplicated for extra reliability.
public region
A region of a physical disk managed by VxVM that contains available space and is used
for allocating subdisks.
RAID
A Redundant Array of Independent Disks (RAID) is a disk array set up with part of the
combined storage capacityused forstoring duplicateinformation aboutthe datastored in
that array. This makes it possible to regenerate the data if a disk failure occurs.