VERITAS Volume Manager 4.1 Administrator's Guide

Glossary
stripe size
Glossary436
stripe size The sum of the stripe unit sizes
comprising a single stripe across all columns
being striped.
stripe unit Equally-sized areas that are
allocated alternately on the subdisks (within
columns) of each striped plex. In an array,
this is a set of logically contiguous blocks
that exist on each disk before allocations are
made from the next disk in the array. A
stripe unit may also be referred to as a stripe
element.
stripe unit size The size of each stripe unit.
The default stripe unit size is 32 sectors
(16K). A stripe unit size has also historically
been referred to as a stripe width.
striping A layout technique that spreads
data across several physical disks using
stripes. The data is allocated alternately to
the stripes within the subdisks of each plex.
subdisk A consecutive set of contiguous
disk blocks that form a logical disk segment.
Subdisks can be associated with plexes to
form volumes.
swap area A disk region used to hold copies
of memory pages swapped out by the system
pager process.
swap volume A VxVM volume that is
configured for use as a swap area.
transaction A set of configuration changes
that succeed or fail as a group, rather than
individually. Transactions are used
internally to maintain consistent
configurations.
volboot file A small file that is used to
locate copies of the rootdg (root disk group)
configuration. The file may list disks that
contain configuration copies in standard
locations, and can also contain direct
pointers to configuration copy locations. A
rootdg that contains only simple disks
requires entries for at least some of those
disks in the volboot file so that vxconfigd can
configure the disk group. The volboot file is
stored in a system-dependent location.
VM disk A disk that is both under VxVM
control and assigned to a disk group. VM
disks are sometimes referred to as VxVM
disks or simply disks.
volume A virtual disk, representing an
addressable range of disk blocks used by
applications such as file systems or
databases. A volume is a collection of from
one to 32 plexes.
volume configuration device The
volume configuration device (/dev/vx/config)
is the interface through which all
configuration changes to the volume device
driver are performed.
volume device driver The driver that
forms the virtual disk drive between the
application and the physical device driver
level. The volume device driver is accessed
through a virtual disk device node whose
character device nodes appear in
/dev/vx/rdsk, and whose block device nodes
appear in /dev/vx/dsk.
volume event log The device interface
(/dev/vx/event) through which volume driver
events are reported to utilities.
vxconfigd The VxVM configuration
daemon, which is responsible for making
changes to the VxVM configuration. This
daemon must be running before VxVM
operations can be performed.