Editing SATA (section)

=== eSATA ===
{{distinguish|SATAe}}
<!-- linked to from redirects -->
[[File:ESATA Logo.svg|upright|thumb|The official eSATA logo]]
[[File:SATA2 und eSATA-Stecker.jpg|thumb|upright|SATA (left) and eSATA (right) connectors]]
[[File:Connector esata IMGP6050 wp.jpg|thumb|upright|[[SATA#eSATA|eSATA]] ports]]

Standardized in 2004, eSATA (''e'' standing for external) provides a variant of SATA meant for external connectivity. It uses a more robust connector, longer shielded cables, and stricter (but backward-compatible) electrical standards. The protocol and logical signaling (link/transport layers and above) are identical to internal SATA. The differences are:
* Minimum transmit amplitude increased: Range is 500–600&nbsp;mV instead of 400–600&nbsp;mV.
* Minimum receive amplitude decreased: Range is 240–600&nbsp;mV instead of 325–600&nbsp;mV.
* Maximum cable length increased to {{convert|2|m|ft|sp=us}} from {{convert|1|m|ft|sp=us}}.
* The eSATA cable and connector is similar to the SATA 1.0a cable and connector, with these exceptions:
** The eSATA connector is mechanically different to prevent unshielded internal cables from being used externally. The eSATA connector discards the L-shaped key and changes the position and size of the guides.
** The eSATA insertion depth is deeper: 6.6&nbsp;mm instead of 5&nbsp;mm. The contact positions are also changed.
** The eSATA cable has an extra shield to reduce [[Electromagnetic interference|EMI]] to FCC and CE requirements. Internal cables do not need the extra shield to satisfy EMI requirements because they are inside a shielded case.
** The eSATA connector uses metal springs for shield contact and mechanical retention.<!-- SATA might also do this -->
** The eSATA connector has a design-life of 5,000 matings; the ordinary SATA connector is only specified for 50.

Aimed at the consumer market, eSATA enters an external storage market served also by the USB and FireWire interfaces. The SATA interface has certain advantages. Most external hard-disk-drive cases with FireWire or USB interfaces use either PATA or SATA drives and "bridges" to translate between the drives' interfaces and the enclosures' external ports; this bridging incurs some inefficiency. Some single disks can transfer 157&nbsp;MB/s during real use,<ref name="Tom2010HardDrives"/> about four times the maximum transfer rate of USB 2.0 or [[IEEE 1394a|FireWire 400 (IEEE 1394a)]] and almost twice as fast as the maximum transfer rate of FireWire 800. The S3200 [[FireWire]] 1394b specification reaches around 400&nbsp;MB/s (3.2&nbsp;Gbit/s), and [[USB 3.0]] has a nominal speed of 5&nbsp;Gbit/s. Some low-level drive features, such as [[Self-Monitoring, Analysis and Reporting Technology|S.M.A.R.T.]], may not operate through some USB<ref>{{cite web |url=http://sourceforge.net/apps/trac/smartmontools/wiki/USB |title=USB – smartmontools |website=sourceforge.net |access-date=2012-01-13 |url-status=dead |archive-url=https://web.archive.org/web/20120207000458/http://sourceforge.net/apps/trac/smartmontools/wiki/USB |archive-date=2012-02-07 }}</ref> or FireWire or USB+FireWire bridges; eSATA does not suffer from these issues provided that the controller manufacturer (and its drivers) presents eSATA drives as ATA devices, rather than as [[SCSI]] devices, as has been common with [[Silicon Image]], [[JMicron]], and [[Nvidia]] nForce drivers for Windows Vista. In those cases SATA drives do not have low-level features accessible.

The eSATA version of SATA&nbsp;6G operates at 6.0&nbsp;Gbit/s (the term "SATA&nbsp;III" is avoided by the [[SATA-IO]] organization to prevent confusion with SATA&nbsp;II 3.0&nbsp;Gbit/s, which was colloquially referred to as "SATA&nbsp;3G" [bit/s] or "SATA&nbsp;300" [MB/s] since the 1.5&nbsp;Gbit/s SATA&nbsp;I and 1.5&nbsp;Gbit/s SATA&nbsp;II were referred to as both "SATA&nbsp;1.5G" [bit/s] or "SATA&nbsp;150" [MB/s]). Therefore, eSATA connections operate with negligible differences between them.<ref>{{cite web |url=http://www.hddlife.com/eng/faq.html |title=Questions about the indicators of health/performance (in percent) |website=hddlife.com |access-date=2007-08-29 |url-status=live |archive-url=https://web.archive.org/web/20070924055228/http://www.hddlife.com/eng/faq.html |archive-date=2007-09-24 }}</ref> Once an interface can transfer data as fast as a drive can handle them, increasing the interface speed does not improve data transfer.

There are some disadvantages, however, to the eSATA interface:
* Devices built before the eSATA interface became popular lack external SATA connectors. 
* For small form-factor devices (such as external 2.5-inch<!-- No unit conversion: this is a nominal size class and not a measurement. --> disks), a PC-hosted USB or FireWire link can usually supply sufficient power to operate the device. However, eSATA connectors cannot supply power, and require a power supply for the external device. The related [[eSATAp]] (but mechanically incompatible, sometimes called ''eSATA/USB'') connector adds power to an external SATA connection, so that an additional power supply is not needed.<ref>{{cite web|url=http://www.sata-io.org/documents/External%20SATA%20WP%2011-09.pdf|title=External Serial ATA|publisher=Silicon Image, Inc|access-date=8 August 2009|url-status=dead|archive-url=https://web.archive.org/web/20100613100125/http://sata-io.org/documents/External%20SATA%20WP%2011-09.pdf|archive-date=13 June 2010}}</ref>

{{As of|2017|8}} few new computers have dedicated external SATA (eSATA) connectors, with USB3 dominating and USB3 Type C, often with the [[Thunderbolt (interface)|Thunderbolt]] alternate mode, starting to replace the earlier USB connectors. Still sometimes present are single ports supporting both USB3 and eSATA.

Desktop computers without a built-in eSATA interface can install an eSATA [[host bus adapter]] (HBA); if the motherboard supports SATA, an externally available eSATA connector can be added. Notebook computers with the now rare [[Cardbus]]<ref name="addonics_cardbus">{{cite web |url=http://www.addonics.com/products/adcb2sa-e.php |title=CardBus SATA adapter |website=addonics.com |access-date=2010-01-26 |url-status=live |archive-url=https://web.archive.org/web/20111104205549/http://www.addonics.com/products/adcb2sa-e.php |archive-date=2011-11-04 }}</ref> or [[ExpressCard]]<ref name="addonics_expresscard">{{cite web |url=http://www.addonics.com/products/adexc34-2e.php |title=ExpressCard SATA adapter |website=addonics.com |access-date=2010-01-26 |url-status=live |archive-url=https://web.archive.org/web/20111129201348/http://www.addonics.com/products/adexc34-2e.php |archive-date=2011-11-29 }}</ref> could add an eSATA HBA. With passive adapters, the maximum cable length is reduced to {{convert|1|m|ft|sp=us}} due to the absence of compliant eSATA signal-levels.

==== eSATAp <span class="anchor" id="eSATAp"></span> ====
{{Main|eSATAp}}
[[File:Esatap port.JPG|thumb|upright|[[eSATAp]] port]]

eSATAp stands for powered eSATA. It is also known as Power over eSATA, Power eSATA, eSATA/USB Combo, or eSATA USB Hybrid Port (EUHP). An eSATAp port combines the four pins of the USB&nbsp;2.0 (or earlier) port, the seven pins of the eSATA port, and optionally two 12&nbsp;V power pins.<ref>{{cite web |url=http://www.addonics.com/technologies/euhp.php |title=Addonics Technology: Hybrid eSATA (eSATA USB hybrid) interface |website=addonics.com |access-date=2011-10-30 |url-status=live |archive-url=https://web.archive.org/web/20111030192542/http://www.addonics.com/technologies/euhp.php |archive-date=2011-10-30 }}</ref> Both SATA traffic and device power are integrated in a single cable, as is the case with USB but not eSATA. The 5&nbsp;V power is provided through two USB pins, while the 12&nbsp;V power may optionally be provided. Typically desktop, but not notebook, computers provide 12&nbsp;V power, so can power devices requiring this voltage, typically 3.5-inch disk and CD/DVD drives, in addition to 5&nbsp;V devices such as 2.5-inch drives.

Both USB and eSATA devices can be used with an eSATAp port, when plugged in with a USB or eSATA cable, respectively. An eSATA device cannot be powered via an eSATAp cable, but a special cable can make both SATA or eSATA and power connectors available from an eSATAp port.

An eSATAp connector can be built into a computer with internal SATA and USB, by fitting a bracket with connections for internal SATA, USB, and power connectors and an externally accessible eSATAp port. Though eSATAp connectors have been built into several devices, manufacturers do not refer to an official standard.

==== Pre-standard implementations ====
* Prior to the final eSATA 6&nbsp;Gbit/s specification many add-on cards and some motherboards advertised eSATA 6&nbsp;Gbit/s support because they had 6&nbsp;Gbit/s SATA 3.0 controllers for internal-only solutions. Those implementations are non-standard, and eSATA 6&nbsp;Gbit/s requirements were ratified in the July 18, 2011 SATA 3.1 specification.<ref>{{cite web |url=https://www.sata-io.org/sites/default/files/documents/SATA-Revision-3.0-FAQ-FINAL.pdf |title=Frequently Asked Questions About SATA 6&nbsp;Gbit/s and the SATA Revision 3.0 Specification |date=May–June 2009 |access-date=2011-10-30 |url-status=live |archive-url=https://web.archive.org/web/20140222150446/https://www.sata-io.org/sites/default/files/documents/SATA-Revision-3.0-FAQ-FINAL.pdf |archive-date=2014-02-22 }}</ref> Some products might not be fully eSATA 6&nbsp;Gbit/s compliant.