HP StorageWorks XP24000 Disk Array Site Preparation Guide, v01 (AE131-96002, June 2007)

Glossary for the HP XP24000 Disk Array
AL Arbitrated loop.
AL-PA Arbitrated loop physical address.
allocation The ratio of allocated storage capacity versus total capacity as a percentage.
“Allocated storage” refers to those LDEVs that have paths assigned to them. The
allocated storage capacity is the sum of the storage of these LDEVs. Total capacity
refers to the sum of the capacity of all LDEVs on the disk array.
array group A group of four identical unformatted disk drives (HDDs). Array groups are
formatted into parity groups (also called RAID groups).
Business Copy The HP StorageWorks XP Business Copy software program, which enables you
to maintain up to nine internal copies of logical volumes on the disk array.
C-Track The HP StorageWorks XP Continuous Track remote support solution, which detects
internal hardware component problems on a disk array and automatically reports
them to the HP STC (Storage Technology Center). C-Track also enables STC
remote diagnosis of the array. There are both internet-based and modem-based
C-Track solutions for the XP24000.
Continuous Access The HP StorageWorks XP Continuous Access program, which enables you to
replicate data stored on a local disk array to a remote disk array.
cache Very high speed memory that is used to speed I/O transaction time. All reads
and writes to the XP array family are sent to the cache. The data is buffered there
until the transfer to/from physical disks (with slower data throughput) is complete.
The benefit of cache memory is that it speeds I/O throughput to the application.
The larger the cache size, the greater the amount of data buffering that can occur
and the greater throughput to the applications.
XP arrays support a range of cache memory. In the event of power loss, battery
power maintains the contents of cache for up to 36 hours.
channel adapter
(CHA)
The channel adapter (CHA) provides the interface between the disk array and
the external host system. Occasionally this term is used synonymously with the
term channel host interface processor (CHIP).
channel processor
(CHP)
The processors located on the channel adapter (CHA).
command device A volume on the disk array that accepts HP StorageWorks XP Continuous Access
or Business Copy control operations which are then executed by the disk array.
control unit To organize the storage space attached to the DKC, you can group similarly
configured logical devices (LDEVs) with unique control unit images (CUs). CUs
are numbered sequentially. The disk array supports a certain number of CUs,
depending on the disk array model. Each CU can manage multiple LDEVs.
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