Avago Technologies MegaRAID SAS 8204ELP - Manual (Page 70)

A-4 Glossary of Terms and Abbreviations
Copyright © 2007 by LSI Corporation. All rights reserved.
server and high-end workstation environments. Each port on the SAS
RAID controller supports SAS devices, SATA II devices, or both.
SAS device Any device that conforms to the SAS standard and is attached to the
SAS bus by a SAS cable. This includes SAS RAID controllers
(host adapters) and SAS peripherals.
SATA Acronym for Serial Advanced Technology Attachment. A physical storage
interface standard, SATA is a serial link that provides point-to-point
connections between devices. The thinner serial cables allow for better
airflow within the system and permit smaller chassis designs.
SMP Acronym for Serial Management Protocol. SMP enables communicates
topology management information directly with an attached SAS
expander device. Each PHY on the controller can function as an SMP
initiator.
SSP Acronym for Serial SCSI Protocol. SSP enables communication with
other SAS devices. Each PHY on the SAS controller can function as an
SSP initiator or SSP target.
STP Acronym for Serial Tunneling Protocol. STP enables communication with
a SATA II device through an attached expander. Each PHY on the SAS
controller can function as an STP initiator.
stripe size The total disk space consumed by a stripe not including a parity disk. For
example, consider a stripe that contains 64 Kbytes of disk space and has
16 Kbytes of data residing on each disk in the stripe. In this case, the
stripe size is 64 Kbytes and the stripe element size is 16 Kbytes. The
stripe depth is four (four physical disks in the stripe). You can specify
stripe sizes of 8 Kbytes, 16 Kbytes, 32 Kbytes, 64 Kbytes, 128 Kbytes,
256 Kbytes, 512 Kbytes, or 1 Mbyte for each virtual disk. A larger stripe
size produces improved read performance, especially if most of the reads
are sequential. For mostly random reads, select a smaller stripe size.
striping Disk striping writes data across two or more disks. Each stripe spans two
or more disks but consumes only a portion of each disk. Each disk,
therefore, may have several stripes. The amount of space consumed by
a stripe is the same on each disk that is included in the stripe. The
portion of a stripe that resides on a single disk is a stripe element.
Striping by itself does not provide data redundancy; striping in
combination with parity provides data redundancy.