Avago Technologies LSI20320 - Manual (Page 30)

24 Fusion-MPT FCode User’s Guide
Copyright © 2000-2004 by LSI Logic Corporation. All rights reserved.
5 Fusion-MPT Special Features
This section describes the FCode interface-to-Fusion-MPT advanced
features. The LSI Logic Fusion-MPT Architecture defines several special
features that can be implemented in the controller chip. These features
include Integrated Mirroring (IM), Integrated Striping (IS), and Integrated
RAID (IR). If your LSI Logic Host Bus Adapter implements one of the
special features, use the information below to access the advanced
functionality.
Note: Not all advanced features are implemented on every host
bus adapter. Check with LSI Logic to determine which host
bus adapters implement which of the advanced features.
5.1 Integrated Mirroring
Disk mirroring, also known as RAID 1, is a storage configuration in which
two physical disks are paired, or “mirrored,” with each other into a set
such that writes to either physical disk are duplicated to the other disk.
The principle advantage of disk mirroring is the ability of the disk set to
survive the failure of a physical disk drive. If a mirrored disk fails, the
Fusion-MPT system instantly switches to the other disk without any loss
of data or service.
To use the Integrated Mirroring feature, you should become familiar with
the following terminology used for mirrored disk sets.
Term Meaning
Related FCode
Commands
Notes
Physical Disk A physical disk drive show-disks
show-children OpenBoot presents volumes as
disks at the show-disks command.
Use the select command first, to
make the desired device active
before using the show-children
command.
Volume Two physical disks presented
to the system as a single vir-
tual disk show-volumes Use the select command first, to
make the desired device active.
Member One of the physical disks cur-
rently in a mirrored volume show-volumes
show-children Use the select command first, to
make the desired device active.