HP Array Controller HSG V8.7 Software - Manual (Page 543)

Glossary G–17
RAM Random access memory.
read ahead caching A caching technique for improving performance of synchronous
sequential reads by prefetching data from disk.
read caching A cache management method used to decrease the subsystem’s
response time to a read request by allowing the controller to satisfy the
request from the cache memory rather than from the disk drives.
reconstruction The process of regenerating the contents of a failed member’s data. The
reconstruct process writes the data to a spareset disk and then
incorporates the spareset disk into the mirrorset, striped mirrorset, or
RAIDset from which the failed member came. See also regeneration.
reduced Indicates that a mirrorset or RAIDset is missing one member because
the member has failed or has been physically removed.
redundancy The provision of multiple interchangeable components to perform a
single function in order to cope with failures and errors. A RAIDset is
considered to be redundant when user data is recorded directly to one
member and all of the other members include associated parity
information.
regeneration (1) The process of calculating missing data from redundant data. (2)
The process of recreating a portion of the data from a failing or failed
drive using the data and parity information from the other members
within the storageset. The regeneration of an entire RAIDset member is
called reconstruction. See also reconstruction.
request rate The rate at which requests are arriving at a servicing entity.
RFI Radio frequency interference. The disturbance of a signal by an
unwanted radio signal or frequency.
replacement policy The policy specified by a switch with the SET FAILEDSET command
indicating whether a failed disk from a mirrorset or RAIDset is to be
automatically replaced with a disk from the spareset. The two switch
choices are AUTOSPARE and NOAUTOSPARE.
SBB StorageWorks building block. (1) A modular carrier plus the interface
required to mount the carrier into a standard StorageWorks shelf. (2)
any device conforming to shelf mechanical and electrical standards