HP A7143A RAID160 SA Controller Support Guide, February 2007

Glossary
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Glossary
ACU (Array Configuration Utility) A
configuration utility useful both for novices and for
more experienced RAID users.
ADU (Array Diagnostic Utility) A diagnostic tool
that collects comprehensive information about the
array controllers in a system and lists any problems
detected.
ARM (Auto-Reliability Monitoring) Also known
as surface analysis. A fault management feature
whereby hard drives are scanned for bad sectors,
and data in the faulty sectors is remapped onto good
sectors. Parity data consistency is also checked for
drives in RAID 5 or RAID ADG configurations.
Operates as a background process.
array A set of physical drives configured into one or
more logical drives. Arrayed drives have significant
performance and data protection advantages over
non-arrayed drives.
array accelerator A component of some Smart
Array controllers that dramatically improves disk
read and write performance by providing a buffer.
Data integrity is protected by a backup battery and
ECC memory.
array capacity expansion See capacity
expansion.
Automatic Data Recovery Also known as rebuild.
A process that automatically reconstructs data from
a failed drive and writes it onto a replacement drive.
Rebuild time depends on several factors, but at least
15 minutes should be allowed per gigabyte.
cache A high-speed memory component, used to
store data temporarily for rapid access.
capacity expansion Abbreviation for array
capacity expansion. The addition of physical drives
to a pre-existing drive array, and redistribution of
existing logical drives and data over the enlarged
array. The size of the logical drives does not change.
capacity extension Abbreviation for logical drive
capacity extension. The enlargement of a logical
drive without disruption of data. There must be free
space on the array before extension can occur. If
necessary, create free space by deleting a logical
drive or by carrying out a capacity expansion.
Capacity extension can be carried out online with
some operating systems.
CISS Acronym for “Command Interface for SCSI-3
Support Specification”.
controller duplexing A type of fault tolerance that
requires two Smart Array controllers. Each
controller has its own set of drives, and the drive
sets have identical data. When one controller fails,
the other automatically takes over the servicing of
requests. controller duplexing is available only for
some operating systems.
data guarding See RAID.
data striping Writing data to logical drives in
interleaved chunks (by byte or by sector). This
technique improves system performance.
drive mirroring See RAID.
ECC (error correction and checking) memory
A type of memory that checks and corrects single-bit
or multi-bit memory errors (depending on
configuration) without causing the server to halt or
corrupt data.
fault tolerance The ability of a server to recover
from hardware problems without interrupting
server performance or corrupting data. Hardware
RAID is most commonly used, but there are other
types of fault tolerance—for example, controller
duplexing and software-based RAID.
flashing Updating the flash memory on a system.
Flash memory is non-volatile memory that is used to
hold control code such as BIOS information. It is also
very fast because it can be rewritten block by block,
rather than byte by byte.
hot spare See online spare.
interim data recovery If a drive fails in RAID 1,
1+0, 5 or ADG, the system will still process I/O
requests, but at a reduced performance level.
logical drive (or logical volume) A group of
physical drives, or part of a group, that behaves as
one storage unit. Each constituent physical drive
contributes the same storage volume to the total
volume of the logical drive. Has performance
advantages over individual physical drives.
logical drive capacity extension See capacity
extension.