Veritas Storage Foundation 5.1 SP1 Advanced Features Administrator"s Guide (5900-1503, April 2011)

extent A logical database attribute that defines a group of contiguous file system data
blocks that are treated as a unit. An extent is defined by a starting block and a
length.
extent attributes An extent allocation policy that is associated with a file and/or file system. See
also address-length pair.
failover The act of moving a service from a failure state back to a running/available state.
Services are generally applications running on machines and failover is the process
of restarting these applications on a second system when the first has suffered a
failure.
file system A collection of files organized together into a structure. File systems are based
on a hierarchical structure consisting of directories and files.
file system block The fundamental minimum size of allocation in a file system.
fileset A collection of files within a file system.
fixed extent size An extent attribute associated with overriding the default allocation policy of the
file system.
fragmentation Storage of data in non-contiguous areas on disk. As files are updated, new data is
stored in available free space, which may not be contiguous. Fragmented files
cause extra read/write head movement, slowing disk accesses.
free space An area of a disk under Veritas Volume Manager control that is not allocated to
any subdisk or reserved for use by any other VxVM object.
gigabyte A measure of memory or storage. A gigabyte is approximately 1,000,000,000 bytes
(technically, 2 to the 30th power, or 1,073,741,824 bytes). Also GB, Gbyte, and
G-byte.
HFS (High Performance
File System)
The HP-UX name for the file system derived from the 4.2 Berkeley Fast File System.
HA (high availability) The ability of a system to perform its function continuously (without significant
interruption) for a significantly longer period of time than the combined
reliabilities of its individual components. High availability is most often achieved
through failure tolerance and inclusion of redundancy; from redundant disk to
systems, networks, and entire sites.
hot backup The process of backing up a database that is online and in active use.
hot pluggable To pull a component out of a system and plug in a new one while the power is still
on and the unit is still operating. Redundant systems can be designed to swap disk
drives, circuit boards, power supplies, CPUs, or virtually anything else that is
duplexed within the computer. Also known as hot swappable.
inode list An inode is an on-disk data structure in the file system that defines everything
about the file, except its name. Inodes contain information such as user and group
Glossary538