Glossary 71
fixed-size OPEN system volumes. Synonymous with volume size
customization (VSC).
disk adapter (DKA) Synonymous with the term ACP.
disk unit (DKU) Array hardware that houses the disk array physical disks.
disk controller (DKC) Array hardware that houses the channel adapters and service processor
(SVP).
disk chassis The housing inside the primary or second rack that contains the physical
disks. The XP10000 primary rack holds up to two disk chassis, and the
second rack holds an additional two disk chassis.
disk recovery and
restore unit (DRR)
The unit responsible for data recovery and restoration in the event of a
cache failure.
disk group The physical disk locations associated with a parity group.
disk type The manufacturing label burned into the physical disk controller firmware.
In most cases, the disk type is identical to the disk model number.
emulation modes The logical devices (LDEVs) associated with each RAID group are
assigned an emulation mode that makes them operate like OPEN system
disk drives. The emulation mode determines the size of an LDEV.
OPEN-3: 2.46 GB
OPEN-8: 7.38 GB
OPEN-9: 7.42 GB
OPEN-E: 13.56 GB
OPEN-K: Not available on XP10000 arrays
OPEN-L: 36 GB
OPEN-M: Not available on XP10000 arrays
OPEN-V: User-defined custom size
EPO Emergency power-off.
ESCON Enterprise System Connection (the IBM trademark for optical channels).
expanded LUN A LUN is normally associated with only a single LDEV. The LUSE feature
allows a LUN to be associated with 1 to 36 LDEVs. Essentially, LUSE
makes it possible for applications to access a single large pool of storage.
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