User Guide

Glossary-3
Version 1.0 Copyright © 2001-2003 by LSI Logic Corporation. All rights reserved.
Cache A temporary storage area for frequently accessed or recently accessed
data. Cache is used to speed up data transfer to and from a disk. See
also Caching.
Cache Flush Refers to an operation where all unwritten blocks in a Write-Back Cache
are written to the target disk. This operation is necessary before
powering down the system.
Cache Line Size Represents the size of the data “chunk” that will be read or written at one
time, and is set in conjunction with stripe size. Under RAID EzAssist
TM
,
the cache line size (also known as Segment Size) should be based on
the stripe size you selected. The default segment size for Mylex RAID
controllers is 8K. See also Stripe Size.
Caching Allows data to be stored in a pre-designated area of a disk or RAM.
Caching speeds up the operation of RAID systems, disk drives,
computers and servers, or other peripheral devices. See also Cache.
Conservative
Cache
An operating mode in which system drives configured with the Write-
Back Caching policy are treated as though they were configured for
Write-Through operation and the cache is flushed.
Consistency
Check
A process that verifies the integrity of redundant data. A consistency
check on a RAID 1 or RAID 0+1 configuration (mirroring) checks if the
data on drives and their mirrored pair are exactly the same. For RAID
Level 3 or RAID Level 5, a consistency check calculates the parity from
the data written on the disk and compares it to the written parity. A
consistency check from Mylex utilities such as Global Array Manager
TM
(GAM) or RAID EzAssist
TM
give the user the ability to have a
discrepancy reported and corrected. See also Parity Check.
Critical State A Logical Drive is in a “critical” state if it has been configured at RAID
level 1, 3, 5, or 0+1, and one (and only one) of its SCSI drives is not
“online.” A logical drive is considered “critical” because any failure of
another of its SCSI drives may result in a loss of data.
Note:
I/O operation can only be performed with system drives that
are online or critical.
Cyclical
Redundancy
Check (CRC)
An error detection tool found on Ultra 160 SCSI (Ultra3 SCSI). This tool
increases the odds for error free data.