Using external SSD in a dock vs. hard drives?

Discussion in 'iMac' started by stanw, Nov 7, 2016.

  1. stanw macrumors 6502a

    Aug 29, 2007
    Using a 2015 5K iMac and an external dock with USB 3, are there noticeable speed gains by plugging in a 1TB Samsung SSD vs. a 7200 RPM hard drive? Does the bandwidth of the USB3 port bottleneck it? Would connecting via thunderbolt make a difference?

  2. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    Yes... an SSD even over a USB3 connection will be FAR faster than a hard drive in every way.

    For a single SSD, Thunderbolt is little if any faster and not normally worth the added cost. TB does allow TRIM where USB does not, so that is an advantage.

    Check this article out.
  3. macmee Suspended


    Dec 13, 2008
    USB3 is fine but when you buy your SSD try to get one with garbage collection since you wont have TRIM
  4. bent christian Suspended

    bent christian

    Nov 5, 2015
    In my experience, the least expensive Thunderbolt solution (Transcend StoreJet 500) is slower than the best consumer-grade USB 3 SSD and enclosure (Samsung Pro 850 SSD/Inateck UASP) by more than 100 MB/Sec.

    TB = 290 MB/Sec write || 380 MB/Sec read
    USB 3 = 400MB/Sec write || 430 MB/Sec read

    A USB 3 set up is cheaper than Thunderbolt by at least $50. There can be a bigger difference in price, depending on the SSD chosen. No TRIM in USB, but this seems to not be such a big deal if you are prepared to give up 20%-30% to free space for file defragging. USB boot enclosures also need idle time for garbage collection. It took me a very long to time figure all of this out. My setup seems to be stable now, and it is very fast.

    Thunderbolt has the advantage of TRIM, which many say doesn't need any free space, as the OS alerts the drive as to where deleted files reside.
  5. phrehdd macrumors 68040


    Oct 25, 2008
    No swag about it, I have the particular USB3 enclosure from that article and the newer (though its not new now) dLite which is a very light enclosure with the same speed. Single SSD in a TBolt enclosure doesn't gain any speed and depending on the set up, might run somewhat slower. TB has an advantage when RAID is involved on a single port.

    As for the dLite -
  6. Fishrrman macrumors G5


    Feb 20, 2009
    USB3 (with the proper enclosure that supports UASP) will be as fast as thunderbolt. No discernable speed difference between them.

    The lack of TRIM shouldn't worry you. In my own experience of booting and running my 2012 Mac Mini via USB3 for almost 4 years now, my SSD's run as fast today as the day I first initialized them and set them up.
    No TRIM = no difference = nothing to worry about.

    Those who keep insisting that TRIM -will- "make a difference" have never tried booting and running via USB3. They have no real-world experience. If they did, they'd be advising you differently, as I am.

    One thing:
    I would suggest you avoid Samsung drives, unless you already have it.
    I'd recommend either Crucial or Sandisk instead.
    My opinion only.

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