Veritas Volume Manager 5.1 SP1 Administrator"s Guide (5900-1506, April 2011)

Persistent FastResync A form of FastResync that can preserve its maps across reboots of the system by
storing its change map in a DCO volume on disk).
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 size or other restrictions. Mirroring is set up by
creating multiple data plexes for a single volume. Each data plex in a mirrored
volume contains an identical copy of the 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.
private disk group A disk group in which the disks are accessed by only one specific host in a cluster.
private region A region of a physical disk used to store private, structured VxVM information.
The private region contains a disk header, a table of contents, and a configuration
database. 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 (redundant array
of independent disks)
A disk array set up with part of the combined storage capacity used for storing
duplicate information about the data stored in that array. This makes it possible
to regenerate the data if a disk failure occurs.
read-writeback mode A recovery mode in which each read operation recovers plex consistency for the
region covered by the read. Plex consistency is recovered by reading data from
blocks of one plex and writing the data to all other writable plexes.
root configuration The configuration database for the root disk group. This is special in that it always
contains records for other disk groups, which are used for backup purposes only.
It also contains disk records that define all disk devices on the system.
root disk The disk containing the root file system. This disk may be under VxVM control.
root file system The initial file system mounted as part of the UNIX kernel startup sequence.
root partition The disk region on which the root file system resides.
root volume The VxVM volume that contains the root file system, if such a volume is designated
by the system configuration.
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