American Megatrends MegaRAID Express 500 Manual Do Utilizador
Glossary
93
Glossary,
Continued
Disk Striping
A type of disk array mapping. Consecutive stripes of data are mapped round-
robin to consecutive array members. A striped array (RAID Level 0) provides
high I/O performance at low cost, but provides lowers data reliability than any of
its member disks.
robin to consecutive array members. A striped array (RAID Level 0) provides
high I/O performance at low cost, but provides lowers data reliability than any of
its member disks.
Disk Subsystem A collection of disks and the hardware that connects them to one or more host
computers. The hardware can include an intelligent controller or the disks can
attach directly to a host computer I/O a bus adapter.
attach directly to a host computer I/O a bus adapter.
Double Buffering A technique that achieves maximum data transfer bandwidth by constantly
keeping two I/O requests for adjacent data outstanding. A software component
begins a double-buffered I/O stream by issuing two requests in rapid sequence.
Thereafter, each time an I/O request completes, another is immediately issued. If
the disk subsystem is capable of processing requests fast enough, double
buffering allows data to be transferred at the full-volume transfer rate.
begins a double-buffered I/O stream by issuing two requests in rapid sequence.
Thereafter, each time an I/O request completes, another is immediately issued. If
the disk subsystem is capable of processing requests fast enough, double
buffering allows data to be transferred at the full-volume transfer rate.
Failed Drive
A drive that has ceased to function or consistently functions improperly.
Fast SCSI
A variant on the SCSI-2 bus. It uses the same 8-bit bus as the original SCSI-1,
but runs at up to 10MB (double the speed of SCSI-1.)
but runs at up to 10MB (double the speed of SCSI-1.)
Firmware
Software stored in read-only memory (ROM) or Programmable ROM (PROM).
Firmware is often responsible for the behavior of a system when it is first turned
on. A typical example would be a monitor program in a computer that loads the
full operating system from disk or from a network and then passes control to the
operating system.
Firmware is often responsible for the behavior of a system when it is first turned
on. A typical example would be a monitor program in a computer that loads the
full operating system from disk or from a network and then passes control to the
operating system.
FlexRAID Power Fail Option The FlexRAID Power Fail option allows a reconstruction to restart
if a power failure occurs. This is the advantage of this option. The disadvantage
is, once the reconstruction is active, the performance is slower because an
additional activity is added.
is, once the reconstruction is active, the performance is slower because an
additional activity is added.
Cont’d