HP StorageWorks XP20000 Disk Array Site Preparation Guide (AE190-96002, September 2007)

Glossary
ACP Array control processor. On some HP XP models, such as the HP XP12000, the
ACP handles the passing of data between the cache and the physical drives.
On other HP XP mo d els, such as the HP XP20 00 0 , this function is handled by
the disk adapter on the MIX board.
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 a rray.
array group A group of 4 or 8 physical hard disk drives (HDDs) installed in a n XP disk
array and assigned a common RAID level. RAID1 array groups consist of four
(2D+2D) or eight HDDs (4D+4D) . RAID5 array groups include a parity disk but
also consist of four (3D+1P) or eight HDDs (7D+1P) . All R AID 6 array groups
are made up of eight HDDs (6D+2P).
ASE Application System Engine er.
BC The H P StorageWorks Business Copy XP software program, which enables you
to maintain up to nine internal copies of logical volumes on the disk array.
C-Track The HP Storage Works Continuous T rack XP software program, which detects
internal hardware component problems on a disk array and automatically
reports themtothe HP STC.
CA The HP StorageWorks Continuous Access XP program, which enables you to
replicatedatastoredon a local diskarray to aremotedisk array.
cache Very high spe ed memory that is used to speed I/O transaction time. All reads
and writes to the HP XP array family are sent to the cache. The data is buffered
there until the transfer to/fro m physical disks (with slower data throughput)
is complete.
The benefit of cache memory is that it speeds I/O throughput to the application.
Thelargerthe cachesize, thegreater theamountofdatabuffering that can
occur and the g reater throughput to the applications.
XP arrays suppor t a range of cache memor y. In the event of power loss, battery
power holds up the contents of c ache for up to 36 hours.
CE Customer engineer.
channel adapter The channel a dapter (CHA) provides the interface between the disk array and
(CHA) the external host system. Occasionally this term is used synonymously with the
term channel host interface processor (CHIP).
channel host in-
Synonymous with the term channel adapter (CHA).
terface processor
(CHIP)
channel processor The processors loc
ated on the channel adapter (CHA) . Synonymous with CHIP.
(CHP)
command d evice A volume on the disk array that accepts Continuous Access o r Business Copy
control operations which are then executed by the disk array.
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