usb 3 ssd as boot drive

Discussion in 'Mac Accessories' started by miatadan, Jan 2, 2014.

  1. miatadan macrumors member

    miatadan

    Joined:
    Apr 23, 2006
    Location:
    Sudbury,ON , Canada
    #1
    If the only usb being used on 2012 mac mini, is a usb 3 ssd fast enough as boot drive?
    Is there ssd software for mac osx to enable trim?

    Dan
     
  2. Fishrrman macrumors G3

    Joined:
    Feb 20, 2009
    #2
    [[ If the only usb being used on 2012 mac mini, is a usb 3 ssd fast enough as boot drive? ]]

    Yes. It will be nearly as fast (or AS FAST) as if you were booting from an internally-connected drive.

    [[ Is there ssd software for mac osx to enable trim? ]]

    No. At least I haven't found any yet.

    Having said that, it doesn't seem to be that much of an issue (or any issue at all). I've been using an Intel 530 series SSD mounted in a plugable.com "lay-flat" USB3/SATA dock for a year now with no issues. Runs fine, boots quickly, sleeps and wakes on command.

    If you want to put an SSD into an enclosure or USB3/SATA dock and "boot externally", just pick the right enclosure.
     
  3. carestudio macrumors 6502

    Joined:
    Aug 6, 2008
    #3
    which USB3 enclosure can let you boot from native USB3 speed?
     
  4. jav6454 macrumors P6

    jav6454

    Joined:
    Nov 14, 2007
    Location:
    1 Geostationary Tower Plaza
    #4
    Fast enough? Depends on the SSD. SATA III and USB 3 have very similar bandwidth sizes (around 6Gb/s each one). So in theory it should be a problem.

    However, if the SSD is designed for faster speeds, then USB 3 will be your bottleneck.
     
  5. Fishrrman macrumors G3

    Joined:
    Feb 20, 2009
    #5
    [[ which USB3 enclosure can let you boot from native USB3 speed? ]]

    You want something with UASP (USB Attached SCSI Protocol). If the enclosure (or USB3/SATA docking station) you're interested in doesn't explicitly state that it supports UASP, no way to know until you try it.

    A few USB3 docks that -do- support UASP:
    http://plugable.com/products/USB3-SATA-U3
    and
    http://plugable.com/products/USB3-SATA-UASP1

    (Disclaimer: I have no affiliation with plugable.com other than being a paying customer.)
     
  6. Weaselboy Moderator

    Weaselboy

    Staff Member

    Joined:
    Jan 23, 2005
    Location:
    California
    #6
    TRIM is not supported over a external USB connection. Only Thunderbolt.
     
  7. ColdCase, Jan 5, 2014
    Last edited: Jan 5, 2014

    ColdCase macrumors 68030

    Joined:
    Feb 10, 2008
    Location:
    NH
    #7
    You are probably not going to notice the difference, but my benchmarks show over 450 MBps for the internal SSD where the same SSD on an external OWC high performance USB3 enclosure is about 235 MBps. A high performance rotational reached ~120 MBps both internally and in the external USB3 enclosure.

    So the SSD internally will seem about twice as fast as the same SSD in a USB3 enclosure because it is more than simple data rate. Remember internal is a native SATA path where USB has a controller and protocol stack, which introduces significant latency, latency that you will notice at rates SSDs support. An external TB SSD should be closer to the internal in data rates because its PCI based. The external USB3 SSD will seem much faster than an internal rotational, however. So fast enough.... sure.

    But how fast is fast for you?
     

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