NAS storage, or Network-attached storage, is a type of computer data storage specializing in server related tasks, such as storing and serving files. NAS devices usually tend to come with several advantages over standard file servers, including faster data access, easier administration, and simpler configuration. This is widely due to the fact that these devices are arranged into what is known as a “redundant array of independent disks”, or a RAID. A RAID contributes to the reliability and stability of the NAS in a number of ways, all of which work together to create one of the most efficient and common computer data storage technologies available.
RAID, or redundant array of independent disks, is essentially an ordered arrangement of separate disk drives. The disk drives are all independent and hold different files, but can be accessed as a single drive by the operating system. Because of this innovative system, the NAS device is considered very efficient. The word RAID is usually seen with a number after it (i.e. RAID 1), which indicate “schemes”. Schemes are what provide the balance between the key goals of a RAID, which are: reliability, availability, performance, and capacity. The importance of these key goals is another key factor in the success of a RAID. A RAID level greater than RAID 0 (RAID zero) indicates protection against unrecoverable read errors and whole disk failure.
Due to the large amount of data being distributed among several drives in a RAID, there needs to be some type of control, or a RAID controller. RAID controllers include a variety of different computer technologies, which all work in completely different ways yet harmoniously come together in the end result.
Types of RAID controllers include raid controller hardware-based RAID, firmware/driver based RAID, software based RAID, and data scrubbing. A hardware-based RAID may be a small component that is integrated into the motherboard. A commonly used controller that supports drive technology is fibre channel, or fibre RAID technology.
Fibre channel is a high speed technology used to connect computer data storage. In the past, it was primarily used in super computers, but now servers as one of the most common connection types for SAV storage. Firmware and driver based RAID was introduced as a result of the high price of hardware RAID controllers. These cheaper controllers contain a standard drive controller rather than a dedicated one. They are loaded with firmware and drivers; the firmware is implemented during early boot-up, while the drivers take control once the operating system has fully loaded.
Another RAID controller type is software-based RAID, which consists of volume manager support, file system support, and operating system support. Finally, the last type of RAID controller is the data-scrubbing controller. Data-scrubbing; also known as patrol reading, is a periodic reading and checking of all blocks in a RAID. This process checks every block, including ones that haven’t been accessed, in order to attempt to detect bad blocks before they are even used. This controller also recovers bad blocks on a single drive.