Which enclosure is faster... USB3 + SSD or Thunderbolt + 7200 HDD

Discussion in 'Mac Accessories' started by talkin73, Nov 25, 2014.

  1. talkin73 macrumors newbie

    Dec 11, 2008
    I boot from my GTech mini USB3 to do repair stuff on my MBPr periodically. It feels as though time is standing still while I wait for it to boot from this external USB3 drive. Felt like my old FW800 was faster with previous MBP but don't have this port on my 2013 MBPr. Looking for faster alternative. Would it be faster to use a USB3 enclosure with something like a Samsung 840 EVO SSD or to use a Thunderbolt enclosure (I know there are precious few of these) with a 7200 RPM HDD? I've looked at the GTech Thunderbolt mini drive with 7200 RPM HDD but was assuming the HDD speed would be the rate limiting step and wouldn't get anywhere near Thunderbolt speeds out of it. Is that correct or would it be considerably faster than USB3 version of the same drive? Then compared to a USB3 enclosure w/ SSD?

    Thanks for any feedback.
  2. ColdCase macrumors 68030

    Feb 10, 2008
    SSD would be much faster regardless of enclosure, you would need to RAID0 a few rotational drives to approach its speed... and SSD have no spin-up wait..

    You would boot faster from a SSD in a thunderbolt enclosure.
  3. matreya macrumors 65816


    Nov 14, 2009
    I would have to agree with this wholeheartedly.

    The best way to date to do this is to buy an enclosure with a hard drive inside, pull the hard drive, and drop in an SSD.

    http://eshop.macsales.com/item/Other World Computing/MOTGTBH5T1.0/

    My suggestion is to get a case like the above and put the hard drive into a cheap USB3 enclosure (also sold by OWC for $27), and use it as a Time Machine backup.
  4. talkin73 thread starter macrumors newbie

    Dec 11, 2008
    Thanks. This is helpful. I read in one of the threads on MacRumors on this general topic that USB3 doesn't support TRIM which can be problematic for an SSD. However, the combo of a USB3 enclosure with SSD seems to be common, much less expensive than a Thunderbolt enclosure and a lot easier to find. Do you know anything about this issue?
  5. talkin73 thread starter macrumors newbie

    Dec 11, 2008
    Thanks for the feedback and suggestion. Much appreciated. After looking at prices and considering what I paid for my DIY 1TB SSD upgrade on my MBPr, I just need to decide if the cost of a Thunderbolt enclosure plus 1TB SSD is worth the speed I'll get for an external backup drive I use once a month. I also have a Time Capsule with TM backups and use CrashplanPro so I do the manual external backups less frequently. Helpful to have this info so I know what I'm getting if I pursue this option. Thanks again.
  6. ColdCase, Nov 26, 2014
    Last edited: Nov 26, 2014

    ColdCase macrumors 68030

    Feb 10, 2008
    That is true, USB does not pass the entire SATA command set, perhaps USB4 will address the issue. Doesn't do NCQ either.

    TB passes the entire command set and since there is no protocol stack, is less quirky, offers best performance, and more robust for HD applications. USB is better suited for other peripherals like mice and keyboards. It does not do well for video either.

    You can get by without trim. Reads are unaffected but writing may eventually slow down but not near as slow as a rotational drive. Unlike magnetic media, when a SSD writes to a memory location full of data it first has to erase the contents of the block (it cannot overwrite gate states). If there is zeroed memory blocks available, the SSD will store (write) new data there and remap the blocks (zero the unused memory block too). The OS keeps track of storage use and errased files, but doesn't bother to tell the drive as it makes no difference to a rotational drive (Writes take the same time regardless of whats there). The trim command allows the OS to to tell the SSD which files/storage location are no longer used (erased or trashed) so it can zero the associated memory blocks in preparation for writes. Makes it a bit more responsive especially as the drive fills up. Without trim, use less than 50% of the SSD's rated capacity and you will probably never notice lack of trim support. There will always be zeroed memory blocks available.

    TB worth the cost is a judgement thing and each has their own value system.
  7. Ray2 macrumors 6502a

    Jul 8, 2014
    Perhaps look at your enclosure or cable. I occasionally boot my wife's MBA off a 7,200 rpm Hitachi in OWC's cheapest 2.5" usb3 enclosure. While its not as quick as the internal ssd, it blows the doors off FireWire 800 which is where I started.

    I've had ssd's in the enclosure as well. As others have pointed out, the lack of spin-up makes for a more immediate response. However, on medium to large size file transfers you won't see much of a difference without moving to Thunderbolt. Depends how important quick occasional maintenance is versus $'s.

    Depending on how you use the external, TRIM may be important. Garbage Collection routines need idle time. If you're just doing maintenance and rebooting to the internal, there's probably no idle time. On the other hand, will you use a "maintenance" ssd enought to even need TRIM?

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