HP A7143A RAID160 SA Controller Support Guide, February 2007

Glossary
LVD (low voltage differential)
Glossary
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LVD (low voltage differential) A type of SCSI
signaling that allows a maximum transfer rate of
either 80 MB/s or 160 MB/s, conforming to either the
Wide Ultra2 or Wide Ultra160 SCSI standards
respectively.
online spare Also known as a hot spare, this is a
drive in a fault-tolerant system that normally
contains no data. When any other drive in the array
fails, the controller automatically rebuilds the
missing data that was on the failed drive onto the
online spare. The controller constructs the missing
data from the duplicate or parity data that is on the
remaining drives in the array.
PCI-X An enhanced PCI bus that allows operation
at 133 MHz, equivalent to a data throughput of
1.0 GB/s. PCI-X is backward-compatible with PCI
systems and devices, which operate at 66 MHz or
33 MHz.
RAID (Redundant Array of Independent
Disks) A form of fault tolerance. RAID 0 (no fault
tolerance) uses data striping to distribute data
evenly across all physical disks in the array, but has
no redundant data. RAID 1+0 (drive mirroring)
duplicates data from one drive onto a second drive.
RAID 5 (distributed data guarding) distributes
parity data across all drives in the array, and uses
the parity data and data on remaining drives to
reconstruct data from a failed drive. RAID ADG
(advanced data guarding) is similar to RAID 5, but
uses two independent sets of parity data. Refer to
Appendix D for more details.
rebuild See Automatic Data Recovery.
SCSI ID A unique ID number assigned to each SCSI
device connected to a SCSI bus. The ID number
determines the device priority on the SCSI bus; ID 7
is the highest priority and is always assigned to the
SCSI controller.
SE (single-ended) A type of SCSI signaling that
allows a maximum transfer rate of 40 MB/s.
Conforms to the Wide-Ultra SCSI standard. Now
being phased out in favor of LVD technology.
S.M.A.R.T. (Self-Monitoring, Analysis, and
Reporting Technology) Technology co-developed
by HP and the hard drive industry that provides
warning of imminent drive failure. This feature
makes it possible for HP to offer Pre-Failure
Warranty replacement of hard drives. S.M.A.R.T.
supersedes the drive parameter tracking feature
that was previously used for this purpose because
the self-monitoring routines used in S.M.A.R.T. are
more accurate than the drive parameter tracking
tests. The self-monitoring routines are customized
for that specific drive type and have direct access to
internal performance, calibration, and error
measurements.
SNMP (Simple Network Management
Protocol) Governs network management and the
monitoring of network devices and functions.
spare See online spare.
striping See data striping.
surface analysis See ARM.
VHDCI (Very High Density Cable
Interconnect) A type of external SCSI connector
used by Ultra SCSI controllers.
Wide-Ultra; Wide Ultra2; Wide Ultra160 A set of
SCSI standards that support maximum signal
transfer rates of 40 MB/s, 80 MB/s, and 160 MB/s,
respectively.