HP StorageWorks 2000fc, Reference Manual

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304 HP StorageWorks 2000 Family Modular Smart Array reference guide • August 2008
cache The location in which data is stored temporarily. There are a variety of
cache types. Read cache holds data in anticipation that it will be
requested. Write cache holds data written by a client until it can be
stored on other (typically slower) storage media such as disk or tape.
(SNIA)
See also write-back cache , write-through cache .
capacitor pack The controller module component that provides backup power to
transfer unwritten data from cache to Compact Flash memory in the
event of a power failure. Storing the data in Compact Flash provides
unlimited backup time. The unwritten data can be committed to the disk
drives when power is restored.
CAPI Configuration application programming interface. The proprietary
protocol used for communication between the Management Controller
and the Storage Controller in a controller module.
channel A physical path used for the transfer of data and control information
between storage devices and a RAID controller or a host; or, a SCSI
bus in a controller module.
CHAP Challenge-Handshake Authentication Protocol.
chassis An enclosure’s metal housing.
chunk size The amount of contiguous data that is written to a virtual disk member
before moving to the next member of the virtual disk. The default
chunk size is 64 Kbyte. The number can be adjusted to improve
performance. Generally, larger chunks are more effective for sequential
reads.
CLI The command-line interface that system administrators can use to
configure, monitor, and manage MSA2000 Family storage systems. The
CLI is accessible from any management host that can access a
controller module through an out-of-band Ethernet or RS-232
connection.
clone A copy of either a master volume or a snapshot.
controller The control logic in a storage subsystem that performs command
transformation and routing, aggregation (RAID, mirroring, striping, or
other), high-level error recovery, and performance optimization for
multiple storage devices. (SNIA)
A controller is also referred to as a RAID controller.