PATA no relation Serial Attached SCSI
History
SATA was announced in 2000 in order to provide several advantages over the earlier PATA interface such as reduced cable size and cost (seven conductors instead of 40 or 80), native hot swapping, faster data transfer through higher signaling rates, and more efficient transfer through an (optional) I/O queuing protocol. Revision 1.0 of the specification was released in January 2003.Serial ATA industry compatibility specifications originate from the Serial ATA International Organization (SATA-IO). The SATA-IO group collaboratively creates, reviews, ratifies, and publishes the interoperability specifications, the test cases and plugfests. As with many other industry compatibility standards, the SATA content ownership is transferred to other industry bodies: primarily INCITS T13 and an INCITS T10 subcommittee (SCSI), a subgroup of T10 responsible for Serial Attached SCSI (SAS). The remainder of this article strives to use the SATA-IO terminology and specifications.
Before SATA's introduction in 2000, PATA was simply known as ATA. The "AT Attachment" (ATA) name originated after the 1984 release of the IBM Personal Computer AT, more commonly known as the IBM AT. The IBM AT's controller interface became a de facto industry interface for the inclusion of hard disks. "AT" was IBM's abbreviation for "Advanced Technology"; thus, many companies and organizations indicate SATA is an abbreviation of "Serial Advanced Technology Attachment". However, the ATA specifications simply use the name "AT Attachment", to avoid possible trademark issues with IBM.SATA host adapters and devices communicate via a high-speed serial cable over two pairs of conductors. In contrast, parallel ATA (the redesignation for the legacy ATA specifications) uses a 16-bit wide data bus with many additional support and control signals, all operating at a much lower frequency. To ensure backward compatibility with legacy ATA software and applications, SATA uses the same basic ATA and ATAPI command sets as legacy ATA devices.
The world's first SATA hard disk drive is the Seagate Barracuda SATA V, which was released in Jan 2003.SATA has replaced parallel ATA in consumer desktop and laptop computers; SATA's market share in the desktop PC market was 99% in 2008. PATA has mostly been replaced by SATA for any use; with PATA in declining use in industrial and embedded applications that use CompactFlash (CF) storage, which was designed around the legacy PATA standard. A 2008 standard, CFast, to replace CompactFlash is based on SATA.Comparison to other interfaces
SATA and SCSI
Parallel SCSI uses a more complex bus than SATA, usually resulting in higher manufacturing costs. SCSI buses also allow connection of several drives on one shared channel, whereas SATA allows one drive per channel, unless using a port multiplier. Serial Attached SCSI uses the same physical interconnects as SATA, and most SAS HBAs also support 3 and 6 Gbit/s SATA devices (an HBA requires support for Serial ATA Tunneling Protocol).
SATA 3 Gbit/s theoretically offers a maximum bandwidth of 300 MB/s per device, which is only slightly lower than the rated speed for SCSI Ultra 320 with a maximum of 320 MB/s total for all devices on a bus. SCSI drives provide greater sustained throughput than multiple SATA drives connected via a simple (i.e., command-based) port multiplier because of disconnect-reconnect and aggregating performance. In general, SATA devices link compatibly to SAS enclosures and adapters, whereas SCSI devices cannot be directly connected to a SATA bus.
SCSI, SAS, and fibre-channel (FC) drives are more expensive than SATA, so they are used in servers and disk arrays where the better performance justifies the additional cost. Inexpensive ATA and SATA drives evolved in the home-computer market, hence there is a view that they are less reliable. As those two worlds overlapped, the subject of reliability became somewhat controversial. Note that, in general, the failure rate of a disk drive is related to the quality of its heads, platters and supporting manufacturing processes, not to its interface.
Use of serial ATA in the business market increased from 22% in 2006 to 28% in 2008.
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