Disk array controller: Difference between revisions

Revision as of 09:13, 27 October 2011

Revision as of 10:33, 27 October 2011

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

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

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 [[emulate]] a disk for a computer

** somewhat less popular protocol dedicated for a specific solution: [[FICON]]/[[ESCON]], [[iSCSI]], [[HyperSCSI]], [[ATA over Ethernet]] or [[InfiniBand]]

A single controller ''may'' use different protocols for back-end and for front-end communication. Many enterprise controllers use FC on front-end and SATA on back-end.

== Enterprise controllers ==