User`s guide

StorageWorks RAID Array 200 Subsystem Family
Terminology
Some of the terms you need to understand as you read this guide are defined as
follows:
Disk array: A set of disk drives and a specialized array controller. The array
controller keeps track of how data is distributed across the drives.
Drive group: A set of drives logically tied together and addressed as a single unit.
ECU: EISA (System) Configuration Utility is used to configure EISA option boards.
JBOD: Sometimes referred to as "just a bunch of disks." Each drive operates
independently and is seen by the operating system as a single drive. There is no data
redundancy in this RAID configuration.
Logical RAID drive: A section of storage space presented to the host operating
system as a single physical drive.
RAID: An acronym for a redundant array of independent (sometimes referred to as
inexpensive) disks.
RAID level: A numerical designator (0 to 5) assigned to each scheme of data
management possible in an array of drives. RAID levels supported by the SWXCR
controller include the following: RAID 0, RAID 0 + 1, RAID 1, and RAID 5.
SBB: System building block. A modular carrier plus the individual mechanical and
electromechanical interface required to mount it into a standard shelf. Any device
conforming to shelf mechanical and electrical standards is considered an SBB.
Write-Back caching: A caching policy in which the controller acknowledges that a
write operation has completed successfully before data is written to the disks. If you
choose this caching policy, you may increase the I/O performance of your RAID
subsystem, but if there is a power failure, you lose data in cache that is not yet written
to the disks.
xii