Raid Controllers

A RAID controller is a hardware device or software program used to manage hard disk drives or solid-state drives in a computer or storage array so they work as a logical unit.

A RAID controller provides a degree of protection for stored data and may also help to improve computing performance by speeding up access to stored data.

What a RAID controller does

A controller offers a level of abstraction between an operating system (OS) and the physical drives. A RAID controller presents groups of or sections of drives to applications and OSes as logical units for which data protection schemes can be defined. The logical units appear as drives -- or portions of drives -- to the applications and OSes, even though they may comprise parts of multiple drives. Because the controller has the ability to access multiple copies of data on multiple physical devices, it has the ability to improve performance and protect data in the event of a system crash.