Manual

Glossary
This glossary defines terms used in this guide or related to this product and is not a comprehensive
glossary of computer terms.
m A symbol for microm eter; one millionth of a meter. For example, 50 mis
equivalent to 0.000050 m.
3U Aunitofme
asurement representing three “U” spaces. “U” spacing is used to
designate panel or enclosure heights. Three “U” spaces is equivalent to 5.25
inches (133 mm).
See also ra
ck-mounting unit.
active m e
mber
of a virtual disk
family
An active
member of a virtual disk family is a simulated disk d rive created
by the controllers as storage for one or more hosts. An active member of a
virtual disk family is accessible by one or more hosts for normal storage. An
active virtual disk mem ber and its snapshot, if one exists, constitute a virtual disk
family. An active member of a virtual disk family is the only necessary member
of a virt
ual disk family.
See also virtual disk,virtual disk copy,virtual disk family ,and snapshot.
adapter See controller.
AL_PA Arbitrated Loop Physical Address. A 1-byte value the arbitrated loop topology
uses to identify the loop ports. This value becomes the last byte of the address
identifier for each public port on the loop.
allocation policy Storage system rules that govern how virtual disks are created. Allocate
Completely and Allocate on Demand are the two rules used in creating virtual
disks.
• Allocate Completely—The space a virtual disk requires on the physical disks
is reserved, even if the virtual disk is not currently using the space.
• Allocate on Demand—The space a virtual disk requires on the physical
disksisnotreserveduntilneeded.
ambient tempera-
ture
The air temperature in the area where a system is installed. Also called inta ke
temperature or room temperature.
ANSI American National Standards Institute. A non-governmental organization that
develops standards (such as SCSI I/O interface standards and Fibre Channel
interface standards) used voluntarily by many manufacturers within the United
States.
arbitrated loop A Fibre Channel topology that links multiple ports (up to 126) together on a
single shared simplex media. Transmissions can only occur between a single
pair of nodes at any given time. Arbitration is the scheme tha t determines which
node has control of the loop at any given m oment
arbitrated loop
physical address
See AL_PA.
arbitrated loop
topology
See arbitrated loop.
array All the physical disk drives in a stora g e system that are known to and under
the co ntrol of a controller pair.
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