Serial ATA

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Modèle:Infobox Computer Hardware Bus

Serial Advanced Technology Attachment (SATA, Modèle:IPAEng or Modèle:IPA) is a computer bus primarily designed for transfer of data between a computer and storage devices (like hard disk drives or optical drives).

The main benefits are faster transfers, ability to remove or add devices while operating (hot swapping), thinner cables that let air cooling work more efficiently, and more reliable operation with tighter data integrity checks than the older Parallel ATA interface.

It was designed as a successor to the legacy Advanced Technology Attachment standard (ATA), and is expected to eventually replace the older technology (retroactively renamed Parallel ATA or PATA). Serial ATA adapters and devices communicate over a high-speed serial cable.

Advanced Host Controller Interface

Main article: Advanced Host Controller Interface

linux-ata.org/driver-status.html#ahci] have native support for AHCI.^{[citation needed]}//linux-ata.org/driver-status.html#ahci] have native support for AHCI.^{[citation needed]}

Features

SATA offers performance as high as 3.0 Gbit/sec per device with the current specification. SATA uses only 4 signal lines, allowing for much more compact (and less expensive) cables compared with PATA. It also offers new features such as hot-swapping and NCQ. There is a special connector (eSATA) specified for external devices, and an optionally implemented provision for clips on internal connectors. SATA drives may be plugged into Serial Attached SCSI (SAS) controllers and communicate on the same physical cable as native SAS disks. SAS disks, however, may not be plugged into a SATA controller.^{[citation needed]}

Throughput

SATA 1.5 Gbit/s

www.tomshardware.com/2007/11/21/samsung_overtakes_with_a_bang/page9.html Samsung Spinpoint F1 HDDs: New Winners?]. Tom's Hardware.</ref> which is well within the performance capabilities of even the older PATA/133 specification.//www.tomshardware.com/2007/11/21/samsung_overtakes_with_a_bang/page9.html Samsung Spinpoint F1 HDDs: New Winners?]. Tom's Hardware.</ref> which is well within the performance capabilities of even the older PATA/133 specification.

During the initial period after SATA/150's finalization, both adapter and drive manufacturers used a "bridge chip" to convert existing designs with the PATA-interface to the SATA-interface.^{[citation needed]} Bridged drives have a SATA connector, may include either or both kinds of power connectors, and generally perform identically to native drives. They generally lack support for some SATA-specific features (such as NCQ). Bridged products gradually gave way to native SATA products.^{[citation needed]}

SATA 3.0 Gbit/s

Soon after SATA/150's introduction, a number of shortcomings in the original SATA were observed. At the application level, SATA's operational model emulated PATA in that the interface could only handle one pending transaction at a time. SCSI disks have long benefited from the SCSI interface's support for multiple outstanding requests, allowing the drive targets to re-order the requests to optimize response time. Native command queuing (NCQ) adds this capability to SATA. NCQ is an optional feature, and may be used in both SATA 1.5 Gbit/s or SATA 3.0 Gbit/s devices.

First-generation SATA devices were scarcely faster than legacy parallel ATA/133 devices. So a 3 Gbit/s signaling rate was added to the Physical layer (PHY layer), effectively doubling data throughput from 150 MB/s to 300 MB/s. SATA/300's transfer rate is expected to satisfy drive throughput requirements for some time, as the fastest desktop hard disks barely saturate a SATA/150 link. This is why a SATA data cable rated for 1.5 Gbit/s will currently handle second generation, SATA 3.0 Gbit/s sustained and burst data transfers without any loss of performance.

www.seagate.com/support/disc/sata/st3250620as.html Barracuda 7200.10 SATA] Seagate.</ref> Known faulty chipsets include the VIA VT8237 and VT8237R south bridges, and the VIA VT6420 and VT6421L standalone SATA controllers.<ref>Service and Support Western Digital.</ref> SiS's 760 and 964 chipsets also initially exhibited this problem, though it can be rectified with an updated SATA controller ROM.^{[citation needed]}//www.seagate.com/support/disc/sata/st3250620as.html Barracuda 7200.10 SATA] Seagate.</ref> Known faulty chipsets include the VIA VT8237 and VT8237R south bridges, and the VIA VT6420 and VT6421L standalone SATA controllers.<ref>Service and Support Western Digital.</ref> SiS's 760 and 964 chipsets also initially exhibited this problem, though it can be rectified with an updated SATA controller ROM.^{[citation needed]}

SATA II Misnomer

The 3.0 Gbit/s specification has been very widely referred to as “Serial ATA II” (“SATA II” or “SATA2“), contrary to the wishes of the The Serial ATA International Organization (SATA-IO) which defines the standard.

SATA 6.0 Gbit/s

www.sata-io.org/portmultiplier.asp |title=Serial ATA Port Multiplier Technology |publisher=SATA-IO |accessdate=2007-07-12}}</ref> Solid-state drives such as RAM disks may also one day make use of the faster transfer rate.//www.sata-io.org/portmultiplier.asp |title=Serial ATA Port Multiplier Technology |publisher=SATA-IO |accessdate=2007-07-12}}</ref> Solid-state drives such as RAM disks may also one day make use of the faster transfer rate.

Cables and connectors

The SATA power and data cables are the most noticeable change from Parallel ATA. Unlike Parallel ATA, the same physical connectors are used on 3.5-in (90 mm) desktop hard disks and 2.5-in (70 mm) notebook disks; this eliminates the need for a mechanical adapter when using a notebook drive in a desktop computer.

The SATA standard defines a data cable with seven conductors (3 grounds and 4 active data lines in two pairs) and 8 mm wide wafer connectors on each end. SATA cables can be up to 1 m (39 in) long, and connect one motherboard socket to one hard drive. PATA ribbon cables, in comparison, connect one motherboard socket to up to two hard drives, carry either 40- or 80-conductor wires, and are limited to 45 cm (18 in) in length by the PATA specification (however, cables up to 90 cm (36 in) are readily available). Thus, SATA connectors and cables are easier to fit in closed spaces and reduce obstructions to air cooling. They are more susceptible to accidental unplugging, but cables can be purchased that have a 'locking' feature, whereby a small (usually metal) spring holds the plug in the socket.

The SATA standard also specifies a new power connector. Like the data cable, it is wafer-based, but its wider 15-pin shape prevents accidental misidentification and forced insertion of the wrong connector type. Native SATA devices favor the SATA power-connector over the old four-pin Molex connector (found on all PATA equipment), although some SATA drives retain older 4-pin Molex. The SATA/power connector has been criticized for its poor robustness—the thin plastic tops of the connectors (see power connector picture at right) can break due to shearing force when the user pulls the plug at a non-orthogonal angle. The seemingly large number of pins are used to supply three different voltages: 3.3 V, 5 V, and 12 V. Each voltage is supplied by three pins ganged together, while ground is provided by five pins. Each pin should be able to provide 1.5 A. Pin 11 is used in newer drives for staggered spinup. The supply pins are ganged together because the small pins by themselves cannot supply sufficient current for some devices. One pin from each of the three voltages is also used for hotplugging.

Adaptors are available to convert a 4-pin Molex connector to SATA power connector. However, because the 4-pin Molex connectors do not provide 3.3 V power, these adapters provide only 5 V and 12 V power and leave the 3.3 V lines disconnected. This precludes the use of such adapters with drives that require 3.3 V power. Understanding this, drive manufacturers have largely left the 3.3 V power lines unused. However, without 3.3 V power, the SATA device may not be able to implement hotplugging as mentioned in the previous paragraph.

External SATA

Standardized in mid-2004, eSATA defined separate cables, connectors, and revised electrical requirements for external applications:

• Minimum transmit potential increased: Range is 500–600 mV instead of 400–600 mV.
• Minimum receive potential decreased: Range is 240–600 mV instead of 325–600 mV.
• Identical protocol and logical signaling (link/transport-layer and above), allowing native SATA devices to be deployed in external enclosures with minimal modification
• Maximum cable length of 2 m (USB and FireWire allow longer distances.)

www.hddlife.com/eng/faq.html |title=Questions about the indicators of health/performance (in percent) |publisher=HDDlife |accessdate=2007-08-29}}</ref> eSATA does not suffer from these issues.//www.hddlife.com/eng/faq.html |title=Questions about the indicators of health/performance (in percent) |publisher=HDDlife |accessdate=2007-08-29}}</ref> eSATA does not suffer from these issues.

eSATA will likely co-exist alongside USB 2.0 and FireWire storage for several reasons. The ubiquity of USB ports on all mass-market computers, and FireWire ports on many consumer electronic appliances, guarantee a large market for USB and FireWire storage.^{[citation needed]} For small form-factor devices (such as external 2.5" (70 mm) disks), a PC-hosted USB or FireWire link supplies sufficient power to operate the device. Where a PC-hosted port is concerned, eSATA connectors cannot supply power, and would therefore be more cumbersome to use.

www.addonics.com/products/host_controller/adcb2sa-e.asp CardBus SATA adapter]</ref> or ExpressCard<ref name="addonics_expresscard">ExpressCard SATA adapter</ref> versions of an eSATA HBA. With passive-adapters, the maximum cable length is reduced to 1 meter, due to the absence of compliant eSATA signal levels. Full SATA speed for external disks (115 MB/s) have been measured with external RAID enclosures.^{[citation needed]}//www.addonics.com/products/host_controller/adcb2sa-e.asp CardBus SATA adapter]</ref> or ExpressCard<ref name="addonics_expresscard">ExpressCard SATA adapter</ref> versions of an eSATA HBA. With passive-adapters, the maximum cable length is reduced to 1 meter, due to the absence of compliant eSATA signal levels. Full SATA speed for external disks (115 MB/s) have been measured with external RAID enclosures.^{[citation needed]}

eSATA may be ignored by the enterprise and server market, which has already standardized on the separately-developed Serial Attached SCSI (SAS) interface, which has extra features for remote management, link redundancy, and link monitoring.^{[citation needed]} The eSATA hotplug capability and consumer-level price-point combination, however, may result in a larger eSATA market share in the enterprise and server market space than would otherwise be expected.

Note: Prior to the final eSATA specification, there were a number of products designed for external connections of SATA drives. Some of these use the internal SATA connector or even connectors designed for other interface specifications, such as FireWire. These products are not eSATA compliant. The final eSATA specification features a specific connector designed for rough manipulation. It's similar to the regular SATA connector, but with reinforcements in both the male and female sides, inspired by the USB connector. It's harder to unplug and can withstand a cable being yanked or wiggled. On a SATA connector, this kind of action will break the male side of the connection (the hard drive or host adapter), rendering the device unusable. With an eSATA connector, considerably more force is needed to damage the connector, and even in this situation, only the female side (the cable itself) will break, possibly leaving the male usable.^{[citation needed]}

Backward and forward compatibility

SATA and PATA

At the device level, SATA and PATA devices are completely incompatible—they cannot be interconnected. At the application level, SATA devices are specified to look and act like PATA devices.<ref> www.sata-io.org/docs/Serialata%20-%20a%20comparison%20with%20Ultra%20ATA%20Technology.pdf |title=A comparison with Ultra ATA Technology |format=PDF |publisher=SATA-IO |accessdate=2007-07-12}}</ref> In early motherboard implementations of SATA, backward compatibility allowed SATA drives to be used as drop-in replacements for PATA drives, even without native (driver-level) support at the operating system level.//www.sata-io.org/docs/Serialata%20-%20a%20comparison%20with%20Ultra%20ATA%20Technology.pdf |title=A comparison with Ultra ATA Technology |format=PDF |publisher=SATA-IO |accessdate=2007-07-12}}</ref> In early motherboard implementations of SATA, backward compatibility allowed SATA drives to be used as drop-in replacements for PATA drives, even without native (driver-level) support at the operating system level.

The common heritage of the ATA command set has enabled the proliferation of low-cost PATA to SATA bridge-chips. Bridge chips were widely used on PATA drives (before the completion of native SATA drives) as well as standalone ‘dongles’. When attached to a PATA drive, a device-side dongle allows the PATA drive to function as a SATA drive. Host-side dongles allow a motherboard PATA port to function as a SATA host port.

Powered enclosures are available for both PATA and SATA drives, which interface to the PC through USB, Firewire or eSATA, with the restrictions noted above. PCI cards with a SATA connector exist that allow SATA drives to connect to legacy systems without SATA connectors.

SATA 1.5Gb/s and SATA 3Gb/s

www.hitachigst.com/hdd/technolo/SerialATA_white_paper.htm Serial ATA - Next Generation Storage Interface] Hitachi Global Storage Technologies.</ref>//www.hitachigst.com/hdd/technolo/SerialATA_white_paper.htm Serial ATA - Next Generation Storage Interface] Hitachi Global Storage Technologies.</ref>

www.seagate.com/support/disc/sata/st3160812as.html Barracuda 7200.9 SATA] Seagate.</ref> Users with a SATA 1.5Gb/s motherboard with one of the listed chipsets should either buy an ordinary SATA 1.5Gb/s hard disk, buy a SATA 3Gb/s hard disk with the user-accessible jumper, or buy a PCI or PCI-E card to add full SATA 3Gb/s capability and compatibility. Western Digital uses jumper setting called "OPT1 Enabled" to force 150 MB/s data transfer speed.//www.seagate.com/support/disc/sata/st3160812as.html Barracuda 7200.9 SATA] Seagate.</ref> Users with a SATA 1.5Gb/s motherboard with one of the listed chipsets should either buy an ordinary SATA 1.5Gb/s hard disk, buy a SATA 3Gb/s hard disk with the user-accessible jumper, or buy a PCI or PCI-E card to add full SATA 3Gb/s capability and compatibility. Western Digital uses jumper setting called "OPT1 Enabled" to force 150 MB/s data transfer speed.

Comparisons with other interfaces

SATA and SCSI

SCSI currently offers transfer rates higher than SATA, but is a more complex bus usually resulting in higher manufacturing cost. Some drive manufacturers offer longer warranties for SCSI devices, however, indicating a possibly higher manufacturing quality control of SCSI devices compared to PATA/SATA devices. SCSI buses also allow connection of several drives (using multiple channels, 7 or 15 on each channel), whereas SATA allows one drive per channel, unless using port multiplier.

SATA 3.0 Gbit/s offers a maximum bandwidth of 300 MB/s per device compared to SCSI with a maximum of 320 MB/s. Also, SCSI drives provide greater sustained throughput than SATA drives because of disconnect-reconnect and aggregating performance. SATA devices are generally compatible with SAS enclosures and adapters, while SCSI devices cannot be directly connected to a SATA bus.

SCSI, SAS and FC drives are typically more expensive, as they are traditionally used in servers and disk arrays. Inexpensive ATA and SATA drives evolved in the home computer market, hence the general opinion is that they are less reliable. As those two worlds started to overlap, the subject of reliability became somewhat controversial. It is worth noting that generally a disk drive has a low failure rate because of increased quality of its heads, platters and supporting manufacturing processes, not because of having a certain interface.

eSATA in comparison to other external buses

Unlike PATA, both SATA and eSATA are designed to support hot-swapping. However, this feature requires proper support at the host, device (drive), and operating-system level. In general, all SATA/devices (drives) support hot-swapping (due to the requirements on the device-side), but requisite support is less common on SATA host adapters.^{[citation needed]}

www.hbe.co.kr/english/download/download_file/HSD314PN_en_manual_v04.pdf#page=6 USB 2.0 Storium Drive] HANBiT Electronics Company.</ref>//www.hbe.co.kr/english/download/download_file/HSD314PN_en_manual_v04.pdf#page=6 USB 2.0 Storium Drive] HANBiT Electronics Company.</ref>

SCSI devices with SCA-2 connectors are designed for hot-swapping. Many server and RAID systems provide hardware support for transparent hot-swapping. The SCSI standard prior to SCA-2 connectors was not designed for hot-swapping, but, in practice, most RAID implementations support hot-swapping of hard disks.

Serial Attached SCSI (SAS) is designed for swapping.

See also

• Advanced Host Controller Interface (AHCI)
• AT Attachment (ATA)
• Compare SATA Bandwidth
• Compare eSATA Bandwidth
• Native Command Queuing (NCQ)

Notes and references

External links

www.sata-io.org/ Serial ATA International Organization ( SATA-IO )]//www.sata-io.org/ Serial ATA International Organization ( SATA-IO )] www.sata-io.org/ Serial ATA International Organization ( SATA-IO )]//www.sata-io.org/docs/serialata10a.zip "SATA-1" specification, as a zipped pdf; Serial ATA: High Speed Serialized AT Attachment, Revision 1.0a, 7-January-2003]. www.sata-io.org/ Serial ATA International Organization ( SATA-IO )]//www.sata-io.org/docs/10a_ECN.zip Errata and Engineering Change Notices to above "SATA-1" specification, as a zip of pdfs] www.sata-io.org/ Serial ATA International Organization ( SATA-IO )]//www.sata-io.org/namingguidelines.asp Dispelling the Confusion: SATA II does not mean 3Gb/s] www.sata-io.org/docs/External%20SATA%20WP%2011-09.pdf SATA-IO White Paper - External SATA (eSATA)]|502 KiB}}//www.sata-io.org/docs/External%20SATA%20WP%2011-09.pdf SATA-IO White Paper - External SATA (eSATA)]|502 KiB}} www.sata-io.org/ Serial ATA International Organization ( SATA-IO )]//pinouts.ru/HD/serialATA_pinout.shtml SATA motherboard connector pinout] www.sata-io.org/ Serial ATA International Organization ( SATA-IO )]//www.intel.com/support/chipsets/imst/sb/CS-020825.htm AHCI/RAID Intel® Matrix Storage Technology: Unattended installation instructions under Windows XP] www.sata-io.org/ Serial ATA International Organization ( SATA-IO )]//support.intel.com/support/chipsets/imsm/sb/CS-021736.htm Intel® Matrix Storage Manager: How do I install an operating system on single serial ATA hard drive?]bs:SATA cs:SATA de:Serial ATA el:SATA es:Serial ATA eo:Serial ATA fr:Serial ATA gl:Serial ATA ko:SATA it:Serial ATA he:Serial ATA hu:Serial ATA lt:Serial ATA nl:Serial ATA ja:シリアルATA no:Serial ATA pl:SATA pt:Serial ATA ru:SATA simple:Serial ATA sk:Serial ATA sr:САТА fi:Serial ATA sv:Serial ATA tr:SATA zh:SATA