Compaq HSZ80 manual GL-12Glossary, Ptl

GL–12Glossary
protocol	The conventions or rules for the format and timing of messages sent and
	received.
PTL	Port-Target-LUN. The controller’s method of locating a device on the
	controller’s device bus.
PVA module	Power Verification and Addressing module.
RAID	Redundant Array of Independent Disks. Represents multiple levels of
	storage access developed to improve performance or availability or both.
RAID level 0	A RAID storageset that stripes data across an array of disk drives. A single
	logical disk spans multiple physical disks, allowing parallel data processing
	for increased I/O performance. While the performance characteristics of
	RAID level 0 are excellent, this RAID level is the only one that does not
	provide redundancy. Raid level 0 storagesets are sometimes referred to as
	stripesets.
RAID level 0+1	A RAID storageset that stripes data across an array of disks (RAID level 0)
	and mirrors the striped data (RAID level 1) to provide high I/O performance
	and high availability. Raid level 0+1 storagesets are sometimes referred to as
	striped mirrorsets.
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 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.