What is RAID controller?
RAID controller, as the name implies, is used for controlling a RAID array. It is the device for managing the physical disk drives for maintaining their functions. RAID controllers also work to control the disks in the RAID so that they work as the logical unit. A RAID controller works towards helping the device to act on RAID recovery.
Types of RAID controllers
Like RAID arrays RAID controllers are also designed exclusively for a type of RAID data recovery system. Hardware of the RAID controller has to be developed for specific hard disks in your system. Therefore, a RAID controller chip that has been designed for IDE-based hard disks cannot be used for an SCSI hard disk.
Likewise, a RAID controller designed for RAID 0 systems will not work on a RAID system with fault tolerant array.
Big manufacturers like Intel, Adaptec, Highpoint, and Promise develop RAID controllers for almost all types of RAID data recovery systems. They come in different forms and you can get them in single CPU or for motherboards with two processor.
For example, Intel motherboards come with RAID controller chips manufactured by them. If you have SCSI-based systems with SCSI cards you would get controller cards for RAIDS on SCSI developed by Adaptec.
Many manufacturers of RAID controller cards prepare non-standard chips that are to be used in specific situations, for example, for 2 U server where the space is very less. Therefore, you will have to get low profile RAID controller cards.
For SATA technologies also you can get SATA controller cards. SATA RAID controller card offered by 3Ware is quite popular these days.
Functions of RAID controllers
RAID controller chips often come within the motherboard for some operating systems. You can also get RAID controllers as PCI extension cards. In these cases you can directly setup RAID 0 and RAID 1 in your computer. But for better actions and effectiveness you should go for dedicated RAID controllers.
Hardware RAID or RAID controllers physically controls the RAID array. RAID controllers in some sense are fully programmed miniature computers. They have dedicated processors. Depending on the method through which hardware RAID interacts with the RAID array, they are classified into two groups-- bus-Based or controller card based and intelligent external RAID controllers.
The first type that is most common is generally used for lower-end RAIDs. Working as an IDE/ATA controller or SCSI host adapter it is installed into the PC/server to directly control the array. Some of these come within the motherboard, especially when they are meant for servers. These are cost effective and flexible.
Intelligent, External RAID Controller is for high-end systems. It is installed in a separate box and it controls the RAID array using SCSI. It presents the logical drives of the RAID array and with the dedicated processor it manages the RAID array. They are costly and difficult to implement as opposed to the bus types.