SAS vs. SATA

SATA and SAS connectors are used to hook up computer components, such as hard drives or media drives, to motherboards. SAS-based hard drives are faster and more reliable than SATA-based hard drives, but SATA drives have a much larger storage capacity. Speedy, reliable SAS drives are typically used for servers while SATA drives are cheaper and used for personal computing. SAS stands for Serial Attached SCSI (pronounced "scuzzy") or Serial Attached Small Computer System Interface, while SATA stands for Serial ATA or Serial Advanced Technology Attachment.

SATA Serial Attached SCSI
Acronym for Serial ATA or Serial Advanced Technology Attachment. Serial Attached SCSI (pronounced "scuzzy") or Serial Attached Small Computer System Interface.
Advantages Inexpensive, large storage capacity. Fast data transfer rate, higher MTBF than SATA (1.2 to 1.6 million hours of use at 45 °C), longer cables, sometimes higher rpm.
Disadvantages Lower MTBF than SAS (700,000 hours to 1.2 million hours of use at 25 °C), less suited for servers. Expensive, less storage capacity, uses more power to operate
Speed Data transfers at the rate of up to 6 Gb/s Data transfers at the rate of up to 6 Gb/s, but generally faster than SATA
Data cable Narrow, can be up to a meter (roughly 3ft) long. Power and data split into two connections. Can be up to 10m (33ft) long. Power and data fused into one connection.
Uses Personal computing, storage. Enterprise, servers.

Speed

Speed Throughput is the amount of data that can be moved, processed, or read and written in a certain amount of time. To measure drive speeds, drive throughput is benchmarked, or tested. (IOPS may also be measured; throughput and IOPS results often suggest the same things about a drive.) The throughput of SAS drives is usually higher than that of SATA drives; there are simply fewer delays in general. However, there is some overlap between slower SAS drives and faster SATA drives. The number of revolutions per minute (rpm) that a drive can perform affects throughput. Several factors affect drive speed on the whole, but generally the higher the rpm, the faster the drive's throughput and similar performance functions will be. Most consumer-level SATA-based drives operate at 5400 rpm and up to 7200 rpm, while most SAS-based drives operate between 7200 rpm and 15000 rpm. This difference in speed is most noticeable when handling large files. A 15000 rpm SAS drive will most likely read and write a 500GB file faster than a 7200 rpm SATA drive will.

Uses/Applications

Personal Computing

While both SATA and SAS drives can be used in personal computing, most small business offices and personal setups will not make regular use of SAS' data transfer capabilities. Sacrificing the storage space of a SATA drive, which typically has at least twice as much hard disk space as a SAS drive for a fraction of the cost, will not be a good trade-off in most all cases.

Servers

When it comes to serving up web pages on a web server or hosting games on a game server, SAS is the superior choice because of its low failure rate and high-speed data transfer capabilities.

Video Explaining Uses

The video below talks further about how SAS and SATA are used.