A RAID Controller is a hardware card or software application used for the purpose of virtualizing multiple hard disks in a server.
The advantages of using RAID is to offer a variety improvements in data storage to address different requirement, namely to improve one or more of the following:
- Data Reliability – i.e. error free data
- Data Availability – i.e. reduced possibility of hardware related data loss
- Data Performance – i.e. fast access to data
- Data Capacity – i.e. high amounts of data stored
The RAID Controller effectively sits between the Operating System (i.e. Linux) and the physical hard drives. It presents the drives as a single logical (virtualised) unit and the type of RAID Controller required depends on the type of RAID being deployed which is dictated by the requirement (see above).
RAID Controller can be either software based or hardware based. Generally hardware based RAID will offer higher levels of performance. Hardware RAID Controllers are usually designed to work specifically with either SATA or SAS based hard drives.