Manual

Glossary
This glossary defines terms used in this guide or related to this product and is not a
comprehensive glossary of computer terms.
A
active member of
a virtual disk
family
An active member of a virtual disk family is a simulated disk drive 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 member 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 virtual disk family.
See also virtual disk,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 disks is not reserved
until needed.
ambient
temperature
The air temperature in the area where a system is installed. Also called intake 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 that determines which node has control of the loop at any given moment
arbitrated loop
physical address
See AL_PA.
arbitrated loop
topology
See arbitrated loop.
array All the physical disk drives in a storage system that are known to and under the control of a
controller pair.
array controller See controller.
asynchronous Events scheduled as the result of a signal requesting the event or that which is without any specified
time relation.
audible alarm The Environmental Monitoring Unit (EMU) alarm that sounds when there is a drive enclosure
element condition report. The audible alarm can be muted or disabled.
B
backplane An electronic printed circuit board that distributes data, control, power, and other signals to
element connectors.
bad block A data block that contains a physical defect.
bad block
replacement
A replacement routine that substitutes defect-free disk blocks for those found to have defects. This
process takes place in the controller and is transparent to the host.
bail lock Part of the power supply AC receptacle that engages the AC power cord connector to ensure
that the cord cannot be accidentally disconnected.
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