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HSG80 Array Controller V8.7 Command Line Interface Reference Guide
Glossary–21
Glossary
RAID level 3/5
A specially developed RAID storageset that stripes data and parity across three or more
members in a disk array. A RAIDset combines the best characteristics of RAID level 3 and
RAID level 5. A RAIDset is the best choice for most applications with small to medium I/O
requests, unless the application is write intensive. A RAIDset is sometimes called parity
RAID. Raid level 3/5 storagesets are referred to as RAIDsets.
RAID level 5
A RAID storageset that, unlike RAID level 3, stores the parity information across all of the
disk drives within the storageset. See also RAID level 3.
RAIDset
See RAID level 3/5
read caching
A cache management method used to decrease the subsystem response time to a read request
by allowing the controller to satisfy the request from the cache memory rather than from the
disk drives.
read-ahead caching
A caching technique for improving performance of synchronous sequential reads by
prefetching data from disk.
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
A term that 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.