3.4 SATA and RAID

SATA is a controller specification. Although it is based on ATA (IDE), it is superior in everyway. For example an IDE controller has a master and a slave channel, but only one can be used (transferring data) at any particular time. On the other hand, each SATA controller only supports one channel. However, multiple SATA controllers can simultaneously transfer data (sharing the system bus, though).

Another advantage of SATA is the availability of external enclosures. This makes it easy to use external hard disks in a server installation. Note that SATA is much faster than USB. SATA II has a maximum transfer rate of 3Gb/s, versus the maximum transfer rate of 480Mb/s of USB.

RAID (redundant array (of) inexpensive drives) is a technique used to enhance the performance and overall reliability of a storage system. Redundancy enhances overall reliability, while striping enhances performance. Both can be implemented at the same time. Note that RAID requires disk drives of symmetric geometry.

RAID and SATA are related because many RAID controllers use SATA to connect to individual drives. In addition, it is also possible to use software to implement RAID (RAID1). Although it is possible to implement RAID1 using IDE, a similar system using SATA will see major performance gain.

The configuration of RAID is out of the scope of this module.