HP Surestore Disk Array 12h and FC60 - Manual (Page 443)

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Class of Service
The types of services provided by the Fibre Channel topology and used by the
communicating port.
controller
A removable unit that contains an array controller.
dacstore
A region on each disk used to store configuration information. During the Start Of Day
process, this information is used to configure controller NVSRAM and to establish other
operating parameters, such as the current LUN configuration.
data redundancy
The technique of storing extra data along with the original data to protect against a disk
failure. This extra, or redundant, data is used to rebuild the original data if a disk fails or
becomes inaccessible. Data redundancy is achieved using one of two techniques:
mirroring or parity.
data transfer rate
Data transfer rate is the speed at which data is transferred between a host computer
system and a peripheral.
degraded mode
The operating mode a LUN enters when if a disk fails or becomes inaccessible. In
degraded mode the LUN must recreate the data on the missing disk using either
mirrored data or parity information. I/O performance typically suffers while the LUN is
in degraded mode. In addition, the LUN is susceptible to a second disk failure while in
degraded mode. The LUN will remain in degraded mode until the content of the failed
disk is rebuilt to a global hot spare or a replacement disk.
DIMM
Dual-inline memory module.