LSI Corporation
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6Gb/s MegaRAID SAS RAID Controllers User Guide
August 2012
Glossary
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 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 an SSP target.
STP Acronym for Serial Tunneling Protocol. STP enables communication with a SATA device through
an attached expander. Each PHY on the SAS controller can function as an STP initiator.
strip The portion of a stripe that resides on a single drive.
stripe size The total drive space consumed by a stripe not including a parity drive. For example, if a stripe
contains 64 KB of drive space and has 16 KB of data residing on each drive, the stripe size is 64 KB
and the strip size is 16 KB.
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 Drive striping writes data across two or more drives. Each stripe spans two or more drives but
consumes only a portion of each drive. Each drive, therefore, may have several stripes. The
amount of space consumed by a stripe is the same on each drive that is included in the stripe.
The portion of a stripe that resides on a single drive is a strip, also known as a stripe element.
Striping by itself does not provide data redundancy; striping in combination with parity provides
data redundancy.
strip size The drive space consumed by a strip. For example, if a stripe contains 64 KB of drive space and
has 16 KB of data residing on each drive, the stripe size is 64 KB and the strip size is 16 KB. The
stripe depth is four (four drives in the stripe). You can specify strip sizes of 8 KB, 16 KB, 32 KB, 64
KB, 128 KB, 256 KB, 512 KB, or 1 MB.
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