Dell PowerEdge RAID Controller 6i - Manual (Page 137)

Glossary
137
Caching
The process of utilizing a high speed memory buffer, referred to as a “cache,” in
order to speed up the overall read or write performance. This cache can be
accessed at a higher speed than a disk subsystem. To improve read performance,
the cache usually contains the most recently accessed data, as well as data from
adjacent disk sectors. To improve write performance, the cache may temporarily
store data in accordance with its write back policies. See the definition of
Write-Back for more information.
Consistency Check
An operation to verify that all stripes in a virtual disk with a redundant RAID
level are consistent and automatically fix any errors. For RAID 5, 6, 50, and 60
arrays, consistency check verifies correct parity data for each stripe. For RAID 1
and RAID 10 arrays, this operation verifies correct mirror data for each stripe.
Controller
A chip that controls the transfer of data between the microprocessor and
memory or between the microprocessor and a peripheral device such as a
physical disk or the keyboard. In Storage Management, the hardware or logic
that interacts with storage devices to write and retrieve data and perform storage
management. RAID controllers perform RAID functions such as striping and
mirroring to provide data protection.
D
DDR SDRAM
Acronym for Double Data Rate Synchronous Dynamic Random Access
Memory. This is a type of SDRAM that provides data throughput at double the
rate of conventional SDRAM. It uses a bursting technique to predict the address
of the next memory location to be accessed and allows two data transfers on
each clock cycle.
Disk
A non-volatile, randomly addressable, rewriteable mass storage device, including
both rotating magnetic and optical storage devices and solid-state storage
devices, or non-volatile electronic storage elements.
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