Filter
Top Products
B-7
Copyright © 2002 by LSI Logic Corporation. All rights reserved.
Redundancy The provision of multiple interchangeable components to perform a
single function to cope with failures or errors. Redundancy normally
applies to hardware; disk mirroring is a common form of hardware
redundancy.
Replacement
Disk
A disk available to replace a failed member disk in a RAID array.
Replacement
Unit
A component or collection of components in a disk subsystem that is
always replaced as a unit when any part of the collection fails. Typical
replacement units in a disk subsystem includes disks, controller logic
boards, power supplies, and cables. Also called a hot spare.
SAF-TE SCSI-accessed fault-tolerant enclosure. An industry protocol for
managing RAID enclosures and reporting enclosure environmental
information.
SCSI (Small computer system interface) A processor-independent standard for
system-level interfacing between a computer and intelligent devices,
including hard disks, floppy disks, CD-ROM, printers, scanners, etc.
Multiple SCSI devices can be connected to a single host adapter on the
computer's bus. SCSI transfers eight or 16 bits in parallel and can
operate in either asynchronous or synchronous modes. The synchronous
transfer rate is up to 320 Mbytes/s (for Ultra320 SCSI). SCSI connections
normally use single-ended drivers, as opposed to differential drivers.
SCSI Channel MegaRAID controls the disk drives through SCSI-2 buses (channels)
over which the system transfers data in either Fast and Wide or Ultra
SCSI mode. Each adapter can control up to three SCSI channels.
Internal and external disk drives can be mixed on channels 0 and 1, but
not on channel 2.
SCSI Drive State A SCSI physical drive can be in one of these states:
· Online: Powered-on and operational.
· Ready: Functioning normally, but not part of a configured logical
drive and not designated as a hot spare.
· Hot Spare: Powered-on stand-by disk drive, ready for use if an
online disk fails.
· Fail: Out of service, due to a fault occurring on the drive.
· Rebuild: Currently being rebuilt with data from a failed drive.