Installation guide

Glossary
G-2 GAM Client v3.00 and WSAM User’s Manual
Cache Line Size
The Cache Line Size function, available in Controller Options or Manual
Configuration, is set in conjunction with stripe size and represents the size of
the data “chunk” that will be read or written at one time. The cache line size
should be based on the stripe size you selected.
Channel
Refers to one bus on a Mylex Disk Array Controller. Each controller
provides at least one channel, and additional channels with optional
upgrades.
Consistency Check
Refers to a process where the integrity of redundant data is verified. For
example, a consistency check of a mirrored drive will make sure that the data
on both drives of the mirrored pair is exactly the same. For RAID Level 5
redundancy, a consistency “connect” is a function that allows a target device
(typically a disk drive that received a request to perform a relatively long I/O
operation) to release the bus so that the controller can send commands to
other devices. When the operation is complete and the bus is needed by the
disconnected target again, it is “reconnected.”
Disk Failure Detection
The controller automatically detects disk failures. A monitoring process
running on the controller checks, among other things, elapsed time on all
commands issued to disks. A time-out causes the disk to be “reset” and the
command to be retried. If the command times out again, the disk could be
“killed” (taken “offline”) by the controller (its state changed to “dead”).
Disk Media Error Management
Mylex Disk Array Controllers transparently manage disk media errors.
Disks are programmed to report errors, even ECC-recoverable errors.
When a disk reports a media error during a read, the controller reads the data
from the mirror (RAID 1 or 0+1), or computes the data from the other blocks
(RAID 3, RAID 5), and writes the data back to the disk that encountered the