HP XP P9500 Storage - Manual (Page 139)

controller The component in a storage system that manages all storage functions. It is analogous to a
computer and contains a processors, I/O devices, RAM, power supplies, cooling fans, and other
sub-components as needed to support the operation of the storage system.
copy pair A pair of volumes in which one volume contains original data and the other volume contains the
copy of the original. Copy operations can be synchronous or asynchronous, and the volumes of
the copy pair can be located in the same storage system (local copy) or in different storage
systems (remote copy).
A copy pair can also be called a volume pair, or just pair.
copy-on-write Point-in-time snapshot copy of any data volume within a storage system. Copy-on-write snapshots
only store changed data blocks, therefore the amount of storage capacity required for each copy
is substantially smaller than the source volume.
COW copy-on-write
CTG See consistency group (CTG).
CTG See consistency group (CTG).
CTL controller
CU control unit
currency of data The synchronization of the volumes in a copy pair. When the data on the secondary volume
(S-VOL) is identical to the data on the primary volume (P-VOL), the data on the S-VOL is current.
When the data on the S-VOL is not identical to the data on the P-VOL, the data on the S-VOL is
not current.
CYL, cyl cylinder
cylinder bitmap Indicates the differential data (updated by write I/Os) in a volume of a split or suspended copy
pair. The primary and secondary volumes each have their own cylinder bitmap. When the pair
is resynchronized, the cylinder bitmaps are merged, and the differential data is copied to the
secondary volume.
DASD direct-access storage device
data consistency When the data on the secondary volume is identical to the data on the primary volume.
data path The physical paths used by primary storage systems to communicate with secondary storage
systems in a remote replication environment.
data pool One or more logical volumes designated to temporarily store original data. When a snapshot is
taken of a primary volume, the data pool is used if a data block in the primary volume is to be
updated. The original snapshot of the volume is maintained by storing the to-be-changed data
blocks in the data pool.
DB database
DBMS database management system
device A physical or logical unit with a specific function.
device emulation Indicates the type of logical volume. Mainframe device emulation types provide logical volumes
of fixed size, called logical volume images (LVIs), which contain EBCDIC data in CKD format.
Typical mainframe device emulation types include 3390-9 and 3390-M. Open-systems device
emulation types provide logical volumes of variable size, called logical units (LUs), that contain
ASCII data in FBA format. The typical open-systems device emulation type is OPEN-V.
DEVN device number
DFW DASD fast write
differential data Changed data in the primary volume not yet reflected in the copy.
disaster recovery A set of procedures to recover critical application data and processing after a disaster or other
failure.
disk array Disk array, or just array, is another name for a RAID storage system.
disk controller
(DKC) The hardware component that manages front-end and back-end storage operations. The term
DKC is sometimes used to refer to the entire RAID storage system.
DKC disk controller. Can refer to the RAID storage system or the controller components.
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