Ssd / usb3 uasp / trim

Discussion in 'iMac' started by MrGimper, Oct 7, 2013.

  1. MrGimper macrumors 603


    Sep 22, 2012
    Andover, UK
    I have a Samsung 830 256GB SSD that I have in a StarTech USB3/UASP Enclosure.

    Getting about 350 MB/s write and 400 MB/s read.

    UASP must be working as I was getting 200 MB/s write and 230 MB/s read in a non-UASP USB3 enclosure.

    Does anyone know if UASP supports TRIM? I know it supports NCQ, but I can't find anything definitive about TRIM support.

  2. bobtennis macrumors member

    Jul 8, 2013
    No, USB 3.0 does not support TRIM, as this is an ACHI command not supported by USB 3.0 standards. UASP is a USB Chipset protocol version for USB 3.0 controllers, and although a faster chip for file transfer, it does not support TRIM commands. Thunderbolt does support TRIM however, as does SATA II & III in ACHI mode (as with all OSX).

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