Disk array controller

In computing, a disk array controller is a computer hardware device which provides secondary storage services to computer systems, often in large servers. It is the critical component of a disk array.
A disk array controller usually attaches to a number of disk drives in disk enclosures which are organised into RAID sets or groups for data protection and performance reasons.
Disk array controllers often provide other services in addition to RAID arrays. These include read cache, write cache and copy services such as Flash Copy and Peer to Peer Remote Copy (PPRC). Various vendors have different terms for these concepts.
Disk array controllers attach to computers using a number of different methods. These include:

• The SCSI command protocol over a Fibre Channel link
• a SAN over either an IP Network (iSCSI) or Fibre Channel
• PCI
  • PCI-X (66/100/133 Mhz)
  • PCI-E (PCI-Express)
  • EISA

The actual disks on the Disk Array Controllers attach to the Controller using an interface technology like:

• Parallel SCSI buses, including the newer wide, fast, and ultra versions of parallel SCSI.
• ESCON or FICON for connecting to a mainframe computer
• The SCSI command protocol over a serial bus such as Serial Attached SCSI
• Serial ATA (SATA)
• Parallel ATA (IDE)

Examples of SATA PCI-Express Controllers:

• Tekram / Areca ARC-1210/1220/1230/1260 SATA-II RAID6 (PCI-E 4/8/12/16 Channel)
• Promise SuperTrak EX8350 8-Port RAID
• Highpoint RocketRAID 2320 PCI-E 8-Port RAID
• Silicon Image 3124