SATA (Serial AT Attachment) is a computer bus interface announced in 2000"Seagate, APT and Vitesse Unveil the First Serial ATA Disc Drive at Intel Developer Forum", Seagate Technology, Aug. 22, 2000 that connects host bus adapters to mass storage devices such as hard disk drives, optical drives, and solid-state drives. Revision 1.0 of the specification was released in January 2003. Serial ATA succeeded the earlier Parallel ATA (PATA) standard to become the predominant interface for storage devices.
Its advantages over the earlier PATA interface include 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.
Serial ATA industry compatibility specifications originate from the Serial ATA International Organization (SATA-IO) which are then released by the INCITS Technical Committee T13, AT Attachment (INCITS T13).
History
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 was the Seagate Barracuda SATA V, released in January 2003.
SATA 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.
Features
Hot plug The Serial ATA spec requires SATA devices be capable of hot plugging; that is, devices that meet the specification are capable of insertion or removal of a device into or from a backplane connector (combined signal and power) that has power on. After insertion, the device initializes and then operates normally. Depending upon the operating system, the host may also initialize, resulting in a hot swap. The powered host and device do not need to be in an idle state for safe insertion and removal, although unwritten data may be lost when power is removed.
Unlike PATA, both SATA and eSATA support hot plugging by design. However, this feature requires proper support at the host, device (drive), and operating-system levels. In general, SATA devices fulfill the device-side hot-plugging requirements, and most SATA host adapters support this function.
For eSATA, hot plugging is supported in AHCI mode only. IDE mode does not support hot plugging.
Advanced Host Controller Interface Advanced Host Controller Interface (AHCI) is an open host controller interface published and used by Intel, which has become a de facto standard. It allows the use of advanced features of SATA such as hotplug and native command queuing (NCQ). If AHCI is not enabled by the motherboard and chipset, SATA controllers typically operate in "IDE emulation" mode, which does not allow access to device features not supported by the ATA (also called IDE) standard.
Windows device drivers that are labeled as SATA are often running in IDE emulation mode unless they explicitly state that they are AHCI mode, in RAID mode, or a mode provided by a proprietary driver and command set that allowed access to SATA's advanced features before AHCI became popular. Modern versions of Microsoft Windows, Mac OS X, FreeBSD, Linux with version 2.6.19 onward, as well as Solaris and OpenSolaris, include support for AHCI, but earlier operating systems such as Windows XP do not. Even in those instances, a proprietary driver may have been created for a specific chipset, such as Intel's.
Revisions SATA revisions are typically designated with a dash followed by Roman numerals, e.g. "SATA-III", to avoid confusion with the speed, which is always displayed in Arabic numerals, e.g. "SATA 6 Gbit/s". The speeds given are the raw interface rate in Gbit/s including line code overhead, and the usable data rate in MB/s without overhead.
SATA revision 1.0 (1.5 Gbit/s, 150 MB/s, Serial ATA-150) Revision 1.0a was released on January 7, 2003. First-generation SATA interfaces, now known as SATA 1.5 Gbit/s, communicate at a rate of 1.5 Gbit/s, and do not support Native Command Queuing (NCQ). Taking 8b/10b encoding overhead into account, they have an actual uncoded transfer rate of 1.2 Gbit/s (150 MB/s). The theoretical burst throughput of SATA 1.5 Gbit/s is similar to that of PATA/133, but newer SATA devices offer enhancements such as NCQ, which improve performance in a multitasking environment.
During the initial period after SATA 1.5 Gbit/s finalization, adapter and drive manufacturers used a "bridge chip" to convert existing PATA designs for use with the SATA interface. Bridged drives have a SATA connector, may include either or both kinds of power connectors, and, in general, perform identically to their native-SATA equivalents.
, the fastest 10,000 rpm SATA hard disk drives could transfer data at maximum (not average) rates of up to 157 MB/s, which is beyond the capabilities of the older PATA/133 specification and also exceeds the capabilities of SATA 1.5 Gbit/s.
SATA revision 2.0 (3 Gbit/s, 300 MB/s, Serial ATA-300)
SATA revision 2.0 was released in April 2004, introducing Native Command Queuing (NCQ). It is backward compatible with SATA 1.5 Gbit/s.
Second-generation SATA interfaces run with a native transfer rate of 3.0 Gbit/s that, when accounted for the 8b/10b encoding scheme, equals to the maximum uncoded transfer rate of 2.4 Gbit/s (300 MB/s). The theoretical burst throughput of the SATA revision 2.0, which is also known as the SATA 3 Gbit/s, doubles the throughput of SATA revision 1.0.
All SATA data cables meeting the SATA spec are rated for 3.0 Gbit/s and handle modern mechanical drives without any loss of sustained and burst data transfer performance. However, high-performance flash-based drives can exceed the SATA 3 Gbit/s transfer rate; this is addressed with the SATA 6 Gbit/s interoperability standard.
SATA revision 2.5 Announced in August 2005, SATA revision 2.5 consolidated the specification to a single document.
SATA revision 2.6 Announced in February 2007, SATA revision 2.6 introduced the following features: Slimline connector Micro connector (initially for 1.8” HDD) Mini Internal Multilane cable and connector Mini External Multilane cable and connector NCQ Priority NCQ Unload Enhancements to the BIST Activate FIS Enhancements for robust reception of the Signature FIS
SATA revision 3.0 (6 Gbit/s, 600 MB/s, Serial ATA-600) Serial ATA International Organization (SATA-IO) presented the draft specification of SATA 6 Gbit/s physical layer in July 2008, and ratified its physical layer specification on August 18, 2008. The full 3.0 standard was released on May 27, 2009.
Third-generation SATA interfaces run with a native transfer rate of 6.0 Gbit/s; taking 8b/10b encoding into account, the maximum uncoded transfer rate is 4.8 Gbit/s (600 MB/s). The theoretical burst throughput of SATA 6.0 Gbit/s is double that of SATA revision 2.0. It is backward compatible with earlier SATA implementations.
The SATA 3.0 specification contains the following changes: 6 Gbit/s for scalable performance. Continued compatibility with SAS, including SAS 6 Gbit/s, as per "a SAS domain may support attachment to and control of unmodified SATA devices connected directly into the SAS domain using the Serial ATA Tunneled Protocol (STP)" from the SATA Revision 3.0 Gold specification. Isochronous Native Command Queuing (NCQ) streaming command to enable isochronous quality of service data transfers for streaming digital content applications. An NCQ management feature that helps optimize performance by enabling host processing and management of outstanding NCQ commands. Improved power management capabilities. A small low insertion force (LIF) connector for more compact 1.8-inch storage devices. A 7 mm optical disk drive profile for the slimline SATA connector (in addition to the existing 12.7 mm and 9.5 mm profiles). Alignment with the INCITS ATA8-ACS standard.
In general, the enhancements are aimed at improving quality of service for video streaming and high-priority interrupts. In addition, the standard continues to support distances up to one meter. The newer speeds may require higher power consumption for supporting chips, though improved process technologies and power management techniques may mitigate this. The later specification can use existing SATA cables and connectors, though it was reported in 2008 that some OEMs were expected to upgrade host connectors for the higher speeds.
SATA revision 3.1 Released in July 2011, SATA revision 3.1 introduced or changed the following features: mSATA, for solid-state drives in mobile computing devices, a PCI Express Mini Card-like connector that is electrically SATA. The connector was also used in some desktop computers, such as certain HP business PCs. Zero-power optical disk drive, a SATA optical drive that draws no power when idle. Queued TRIM Command, improves solid-state drive performance. Required Link Power Management, reduces overall system power demand of several SATA devices. Hardware Control Features, enable host identification of device capabilities. Universal Storage Module (USM), a new standard for cableless plug-in (slot) powered storage for consumer electronics devices.
SATA revision 3.2 Released in August 2013, SATA revision 3.2 introduced the following features: The SATA Express specification defines an interface that combines both SATA and PCI Express buses, making it possible for both types of storage devices to coexist. By employing PCI Express, a much higher theoretical throughput of 1969 MB/s is possible.Enabling Higher Speed Storage Applications with SATA Express , Serial ATA International Organization.SATA-IO announces 16Gb/s SATA 3.2 specification . The SATA M.2 standard is a small form factor implementation of the SATA Express interface, with the addition of an internal USB 3.0 port; see the M.2 (NGFF) section below for a more detailed summary. microSSD introduces a ball grid array electrical interface for miniaturized, embedded SATA storage.SATA μSSD , Serial ATA International Organization. USM Slim reduces thickness of Universal Storage Module (USM) from to .