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{{As of|August 2011}}, only the [[NEC]]/[[Renesas]] chips had UAS drivers.<ref>{{cite web|author=TeamVR |url=http://vr-zone.com/articles/usb-3-0-speed-tests-7-way-host-controllers-roundup/13358.html |title=USB 3.0 Speed Tests: 7-Way Host Controllers Roundup - Page 1 of 11 |publisher=Vr-zone.com |date=August 23, 2011 |accessdate=2014-01-19}}</ref> In October 2011, [[ASMedia]] chips had gained driver support as well (theyhad support on the hardware side had before).<ref>http://vr-zone.com/articles/asus-launches-usb-3-0-speed-booster-uasp-support-for-asmedia/13732.html</ref> The same Renesas UAS driver (for Windows) also works with AMD's [[Comparison_of_AMD_chipsets#Fusion_controller_hubs_.28FCH.29|A70M and A75 Fusion Controller]] Hubs,<ref>http://www.electronics-eetimes.com/en/usb-to-sata3-bridge-supports-uasp.html?cmp_id=7&news_id=222908986</ref> the USB part of which was co-developed by AMD and Renesas.<ref>http://semiaccurate.com/2011/03/23/amds-a75-and-a70m-fch-gains-usb-if-approval/</ref>
{{As of|August 2011}}, only the [[NEC]]/[[Renesas]] chips had UAS drivers.<ref>{{cite web|author=TeamVR |url=http://vr-zone.com/articles/usb-3-0-speed-tests-7-way-host-controllers-roundup/13358.html |title=USB 3.0 Speed Tests: 7-Way Host Controllers Roundup - Page 1 of 11 |publisher=Vr-zone.com |date=August 23, 2011 |accessdate=2014-01-19}}</ref> In October 2011, [[ASMedia]] chips had gained driver support as well (theyhad support on the hardware side had before).<ref>http://vr-zone.com/articles/asus-launches-usb-3-0-speed-booster-uasp-support-for-asmedia/13732.html</ref> The same Renesas UAS driver (for Windows) also works with AMD's [[Comparison_of_AMD_chipsets#Fusion_controller_hubs_.28FCH.29|A70M and A75 Fusion Controller]] Hubs,<ref>http://www.electronics-eetimes.com/en/usb-to-sata3-bridge-supports-uasp.html?cmp_id=7&news_id=222908986</ref> the USB part of which was co-developed by AMD and Renesas.<ref>http://semiaccurate.com/2011/03/23/amds-a75-and-a70m-fch-gains-usb-if-approval/</ref>


[[Microsoft]] added native support for UAS to [[Windows 8]].<ref>http://plugable.com/2012/10/25/usb-3-0-support-on-windows-8</ref> Windows 8 supports UAS by default over USB 2.0 as well.<ref>[http://msdn.microsoft.com/en-us/library/windows/hardware/jj248714.aspx USB Attached SCSI (UAS) Best Practices for Windows 8], page 6</ref> UAS drivers and products are certified by Microsoft using the [[Windows Hardware Certification Kit]].<ref>http://msdn.microsoft.com/en-us/library/windows/hardware/hh998035.aspx</ref> {{As of|2012}} the [[Linux kernel]] also had native UAS support, but it had compatibility problems with Texas Instruments chips.<ref>http://e2e.ti.com/support/interface/digital_interface/f/130/p/168515/617002.aspx#617002</ref>
[[Microsoft]] added native support for UAS to [[Windows 8]].<ref>http://plugable.com/2012/10/25/usb-3-0-support-on-windows-8</ref> Windows 8 supports UAS by default over USB 2.0 as well.<ref>[http://msdn.microsoft.com/en-us/library/windows/hardware/jj248714.aspx USB Attached SCSI (UAS) Best Practices for Windows 8], page 6</ref> UAS drivers and products are certified by Microsoft using the [[Windows Hardware Certification Kit]].<ref>http://msdn.microsoft.com/en-us/library/windows/hardware/hh998035.aspx</ref> {{As of|2012}} the [[Linux kernel]] also had native UAS support, but it had compatibility problems with Texas Instruments chips.<ref>http://e2e.ti.com/support/interface/digital_interface/f/130/p/168515/617002.aspx#617002</ref> The Linux driver had "BROKEN" status until September 2013.<ref>http://linux-kernel.2935.n7.nabble.com/PATCH-5-5-uas-remove-BROKEN-td712925.html</ref>


== Goals ==
== Goals ==

Revision as of 01:27, 20 January 2014

USB Attached SCSI (UAS) is a computer protocol used to move data to and from USB storage devices such as hard drives, solid-state drives, and thumb drives. UAS depends on the USB protocol, and uses the standard SCSI command set. UAS was introduced in the USB 3.0 standard, but can be used for slower USB 2.0 devices assuming compatible hardware/firmware/drivers.

UAS is defined across two standards, the T10 "USB Attached SCSI" (T10/2095-D) referred to as the "UAS" specification, and the USB "Universal Serial Bus Mass Storage Class - USB Attached SCSI Protocol (UASP)" specification. The T10 technical committee of the International Committee for Information Technology Standards (INCITS) develops and maintains the UAS specification; the SCSI Trade Association (SCSITA) promotes the UAS technology. The USB mass-storage device class (MSC) Working Group develops and maintains the UASP specification; the USB Implementers Forum, Inc. (USB-IF) promotes the UASP technology.

UAS drivers generally provide faster transfers compare to the older USB Mass Storage Bulk-Only Transfer (BOT) protocol drivers.[1][2][3] Although UAS was added in the USB 3.0 standard, it can also be used at USB 2.0 speeds, assuming compatible hardware.[4]

As of August 2011, only the NEC/Renesas chips had UAS drivers.[5] In October 2011, ASMedia chips had gained driver support as well (theyhad support on the hardware side had before).[6] The same Renesas UAS driver (for Windows) also works with AMD's A70M and A75 Fusion Controller Hubs,[7] the USB part of which was co-developed by AMD and Renesas.[8]

Microsoft added native support for UAS to Windows 8.[9] Windows 8 supports UAS by default over USB 2.0 as well.[10] UAS drivers and products are certified by Microsoft using the Windows Hardware Certification Kit.[11] As of 2012 the Linux kernel also had native UAS support, but it had compatibility problems with Texas Instruments chips.[12] The Linux driver had "BROKEN" status until September 2013.[13]

Goals

  • Designed to directly address the failings of the USB mass-storage device class bulk-only transports (BOT)
    • Enables command queuing and out-of-order completions for USB mass-storage devices
    • Eliminates software overhead for SCSI command phases
  • Up to 64K commands may be queued
  • SCSI SAM-4 compliant
  • USB 3.0 SuperSpeed and USB 2.0 High-Speed versions defined
    • USB 3.0 SuperSpeed – host controller (xHCI) hardware support, no software overhead for out-of-order commands
    • USB 2.0 High-speed – Significantly enables command queuing in USB 2.0 drives
  • Streams were added to the USB 3.0 SuperSpeed protocol for supporting UAS out-of-order completions
    • USB 3 host controller (xHCI) provides hardware support for streams

References

  1. ^ Lars-Göran Nilsson (2010-07-30). "Gigabyte adds UASP support to its USB 3.0 motherboards". SemiAccurate. Retrieved 2014-01-19.
  2. ^ Andrew Ku (2012-06-19). "USB Attached SCSI (UAS): Enabling Even Better USB 3.0 Performance - Faster USB 3.0 Performance: Examining UASP And Turbo Mode". Tomshardware.com. Retrieved 2014-01-19.
  3. ^ http://electronicdesign.com/embedded/whats-difference-between-usb-uasp-and-bot?page=2
  4. ^ Lars-Göran Nilsson (2010-08-11). "Gigabyte's UASP USB 3.0 driver boosts USB 2.0 performance". SemiAccurate. Retrieved 2014-01-19.
  5. ^ TeamVR (August 23, 2011). "USB 3.0 Speed Tests: 7-Way Host Controllers Roundup - Page 1 of 11". Vr-zone.com. Retrieved 2014-01-19.
  6. ^ http://vr-zone.com/articles/asus-launches-usb-3-0-speed-booster-uasp-support-for-asmedia/13732.html
  7. ^ http://www.electronics-eetimes.com/en/usb-to-sata3-bridge-supports-uasp.html?cmp_id=7&news_id=222908986
  8. ^ http://semiaccurate.com/2011/03/23/amds-a75-and-a70m-fch-gains-usb-if-approval/
  9. ^ http://plugable.com/2012/10/25/usb-3-0-support-on-windows-8
  10. ^ USB Attached SCSI (UAS) Best Practices for Windows 8, page 6
  11. ^ http://msdn.microsoft.com/en-us/library/windows/hardware/hh998035.aspx
  12. ^ http://e2e.ti.com/support/interface/digital_interface/f/130/p/168515/617002.aspx#617002
  13. ^ http://linux-kernel.2935.n7.nabble.com/PATCH-5-5-uas-remove-BROKEN-td712925.html
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