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

cluster-shareable disk
group
A disk group in which access to the disks is shared by multiple hosts (also referred
to as a shared disk group).
column A set of one or more subdisks within a striped plex. Striping is achieved by
allocating data alternately and evenly across the columns within a plex.
concatenation A layout style characterized by subdisks that are arranged sequentially and
contiguously.
configuration copy A single copy of a configuration database.
configuration database A set of records containing detailed information on existing VxVM objects (such
as disk and volume attributes).
DCO (data change
object)
A VxVM object that is used to manage information about the FastResync maps in
the DCO volume. Both a DCO object and a DCO volume must be associated with a
volume to implement Persistent FastResync on that volume.
data stripe This represents the usable data portion of a stripe and is equal to the stripe minus
the parity region.
DCO volume A special volume that is used to hold Persistent FastResync change maps and
dirty region logs. See also see dirty region logging.
detached A state in which a VxVM object is associated with another object, but not enabled
for use.
device name The device name or address used to access a physical disk, such as c0t0d0. The
c#t#d# syntax identifies the controller, target address, and disk.
In a SAN environment, it is more convenient to use enclosure-based naming,
which forms the device name by concatenating the name of the enclosure (such
as enc0) with the disk’s number within the enclosure, separated by an underscore
(for example, enc0_2). The term disk access name can also be used to refer to a
device name.
dirty region logging The method by which the VxVM monitors and logs modifications to a plex as a
bitmap of changed regions. For a volumes with a new-style DCO volume, the dirty
region log (DRL) is maintained in the DCO volume. Otherwise, the DRL is allocated
to an associated subdisk called a log subdisk.
disabled path A path to a disk that is not available for I/O. A path can be disabled due to real
hardware failures or if the user has used the vxdmpadm disable command on that
controller.
disk A collection of read/write data blocks that are indexed and can be accessed fairly
quickly. Each disk has a universally unique identifier.
disk access name An alternative term for a device name.
Glossary562