performance characteristics of RAID level 0 is excellent, this RAID level is
the only one that does not provide redundancy. Raid level 0 storagesets are
referred to as stripesets.
RAID 1
SNIA dictionary definition: A form of storage array in which two or more
identical copies of data are maintained on separate media. (S)
IBM definition: A form of storage array in which two or more identical
copies of data are maintained on separate media. Also known as mirrorset.
HP definition: See mirrorset.
RAID 5
SNIA definition: A form of parity RAID in which the disks operate
independently, the data strip size is no smaller than the exported block
size, and parity check data is distributed across the array’s disks. (S)
IBM definition: See the SNIA definition.
HP definition: 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 10
A type of RAID that optimizes high performance while maintaining fault
tolerance for up to two failed disk drives by striping volume data across
several disk drives and mirroring the first set of disk drives on an identical
set.
redundant ac power switch
A device that provides input power redundancy by attaching a SAN
Volume Controller to two independent power sources. If the main source
becomes unavailable, the redundant ac power switch automatically
provides power from a secondary (backup) source. When power is
restored, the redundant ac power switch automatically changes back to the
main power source.
redundant array of independent disks (RAID)
A collection of two or more disk drives that present the image of a single
disk drive to the system. In the event of a single device failure, the data
can be read or regenerated from the other disk drives in the array.
redundant SAN
A storage area network (SAN) configuration in which any one single
component might fail, but connectivity between the devices within the
SAN is maintained, possibly with degraded performance. This
configuration is normally achieved by splitting the SAN into two,
independent, counterpart SANs. See also counterpart SAN.
reference
A pointer to another instance that defines the role and scope of an object in
an association.
rejected
A status condition that describes a node that the cluster software has
removed from the working set of nodes in the cluster.
178 IBM System Storage SAN Volume Controller: Hardware Installation Guide
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