HP Surestore Disk Array 12h - And FC60 Service Manual page 400

parity
A data protection technique that provides data redundancy by creating extra data based
on the original data. Parity is calculated on each write I/O by doing a serial binary
exclusive OR (XOR) of the data segments in the stripe written to the data disks in the
LUN. Parity is used by RAID 5 LUNs to reconstruct data from a failed disk.
peripheral device addressing (PDA)
The addressing technique used by the host to address the disk array controllers.
Because it is limited to addressing only eight LUNs, PDA has been superseded by VSA
as the technique for addressing disk array LUNs.
point-to-point
One of three existing Fibre Channel topologies, in which two devices are directly
connected by a link with no fabric, loop, or switching elements present.
port
The hardware entity that connects a device to a Fibre Channel topology. A device can
contain one or more ports.
primary disk array path or primary path
The main data path used for host I/Os to a LUN. The primary path can be set using LVM.
Because the disk array has two controllers, one controller acts as the primary path, and
the other acts as the alternate path. If a failure occurs in the primary data path, the
alternate path is used, maintaining access to the LUN.
PROM (Programmable Read-Only Memory)
SP-resident boot code that loads the SP microcode from one of the disk array's
database drives when the disk array is powered up or when an SP is enabled.
RAID
An acronym for "Redundant Array of Independent Disks." RAID was developed to
provide data redundancy using independent disk drives. RAID is essentially a method
for configuring multiple disks into a logical entity (LUN) that appears to the host system
as a single, contiguous disk drive. RAID uses features such data striping, disk mirroring,
400