Disk array controller: Difference between revisions

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A '''disk array controller''' is a device which manages the physical [[disk drives]] and presents them to the computer as [[Logical Unit Number|logical units]]. It almost always implements [[RAID#Hardware-based|hardware]] [[RAID]], thus it is sometimes referred to as '''RAID controller'''. It also often provides additional disk [[cache (computing)|cache]].

A ''disk array controller'' name is oftenoiften improperly shortened to a ''[[disk controller]]''. The two should not be confused as they provide very different functionality.

== Front-end and back-end side ==

A disk array controller provides front-end interfaces and back-end interfaces.

* Back-end interface communicates with controlled disks. Hence protocol is usually [[Advanced Technology Attachment|ATA]] (a.k.a. PATA; incorrectly called IDE), [[Serial ATA|SATA]], [[SCSI]], [[Fibre Channel|FC]] or [[Serial Attached SCSI|SAS]].

* Front-end interface communicates with a computer's [[host adapter]] (HBA, Host Bus Adapter) and uses:

** one of ATA, SATA, SCSI, FC; these are popular protocols used by disks, so by using one of them a controller may transparently [[emulator|emulate]] a disk for a computer