HP StorageWorks HSG80 Array Controller V8.7 Maintenance And Service Manual page 176

Glossary
RAID level 1
A RAID storageset of two or more physical disks that maintains a complete and independent
copy of the entire virtual disk's data. This type of storageset has the advantage of being highly
reliable and extremely tolerant of device failure. Raid level 1 storagesets are sometimes
referred to as mirrorsets.
RAID level 3
A RAID storageset that transfers data parallel across the array's disk drives a byte at a time,
causing individual blocks of data to be spread over several disks serving as one enormous
virtual disk. A separate redundant check disk for the entire array stores parity on a dedicated
disk drive within the storageset. See also RAID level 5.
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 sometimes 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
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.
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.
Glossary–10 HSG80 Array Controller V8.7 Maintenance and Service Guide