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

(for example, enc0_2). The term disk access name can also be used to refer to a
device name.
direct I/O An unbuffered form of I/O that bypasses the kernel’s buffering of data. With direct
I/O, data is transferred directly between the disk and the user application.
Dirty Region Logging The procedure by which the Veritas Volume Manager monitors and logs
modifications to a plex. A bitmap of changed regions is kept in an associated
subdisk called a log subdisk.
disk access name An alternative term for a device name.
disk array A collection of disks logically and physically arranged into an object. Arrays
provide benefits including data redundancy and improved performance.
disk cache A section of RAM that provides a cache between the disk and the application. Disk
cache enables the computer to operate faster. Because retrieving data from hard
disk can be slow, a disk caching program helps solve this problem by placing
recently accessed data in the disk cache. Next time that data is needed, it may
already be available in the disk cache; otherwise a time-consuming operation to
the hard disk is necessary.
disk group A collection of disks that share a common configuration.
A disk group configuration is a set of records containing detailed information on
existing Veritas Volume Manager objects (such as disk and volume attributes) and
their relationships. Each disk group has an administrator-assigned name and an
internally defined unique ID. The root disk group (rootdg) is a special private disk
group.
disk name A Veritas Volume Manager logical or administrative name chosen for the disk,
such as disk03. The term disk media name is also used to refer to the disk name.
Dynamic Multipathing See DMP.
Decision Support
Systems
See DSS.
DMP (Dynamic
Multipathing)
A Veritas Volume Manager feature that allows the use of multiple paths to the
same storage device for load balancing and redundancy.
error handling Routines in a program that respond to errors. The measurement of quality in
error handling is based on how the system informs the user of such conditions
and what alternatives it provides for dealing with them.
evacuate Moving subdisks from the source disks to target disks.
exabyte A measure of memory or storage. An exabyte is approximately
1,000,000,000,000,000,000 bytes (technically 2 to the 60th power, or
1,152,921,504,606,846,976 bytes). Also EB.
537Glossary