Replacing the internal drive with an external one?

Discussion in 'iMac' started by sultanoflondon, Apr 17, 2016.

  1. sultanoflondon macrumors regular

    Joined:
    Dec 3, 2013
    #1
    Hi all,

    I have been advised to replace my internal HDD of my 2012 iMac. I was wondering whether it is possible and feasible to switch the system drive from the internal HDD to an external HDD? Could I just buy an external HDD and tell the iMac to run from this, instead of going through the hassle and risk of replacing the internal HDD? Also, if I did this, would there be any negative impact on computer performance?

    Thank you!
     
  2. cyclingplatypus macrumors 6502a

    cyclingplatypus

    Joined:
    Mar 15, 2007
    Location:
    Earth
    #2
    You can do this, the speed difference would be negligible especially if you used an SSD or hybrid drive. I don't have a 2012 iMac but I believe it has USB3 - if not you could go with the pricier thunderbolt enclosure/drive route.
     
  3. sultanoflondon thread starter macrumors regular

    Joined:
    Dec 3, 2013
    #3
    Thank you for your reply.

    I would use a 1TB external SSD directly connected to the iMac's USB 3.0 port. In fact, I was considering this drive:

    http://www.amazon.co.uk/dp/B01AAKZRMK/ref=olp_product_details?_encoding=UTF8&me=#Ask

    Do you have any information or links on how to transfer the startup disk to the external HDD and how to transfer all the content with it? I guess I could do this using a Time Machine backup?

    Thank you!
     
  4. Weaselboy Moderator

    Weaselboy

    Staff Member

    Joined:
    Jan 23, 2005
    Location:
    California
    #4
    That Samsung device you linked will work, but looks horribly overpriced. I would get a 1tb Samsung EVO 850 along with a UASP USB3 external enclosure like this one for far less money.

    Just put the new SSD in the enclosure and attach, then use Disk Utility to format the SSD to Mac OS Extended (Journaled) format. Then use the free 30 day trial of Carbon Copy Cloner to clone the internal to the external. Then reboot and hold the option key to select the external as the boot drive. The lastly open System Preferences and in the Startup Disk panel select the SSD as the boot drive so it will by default boot to that drive in the future.

    The only downside to this setup is USB does not support TRIM on an SSD, but that is not big deal.
     
  5. cyclingplatypus macrumors 6502a

    cyclingplatypus

    Joined:
    Mar 15, 2007
    Location:
    Earth
    #5
    I agree with Weaselboy on both accounts, Carbon Copy Cloner is a great app and that drive you linked to is overpriced.

    Here is the same drive for $400. I would personally buy a drive and enclosure separately.
     
  6. stuartak macrumors member

    stuartak

    Joined:
    Feb 21, 2016
    #6
    Not supporting trim will eventually bite you , as the SSD will get slower , this will only start to be noticeable as it fills up the drive , overwriting previously written cells on an SSD slows it down , trim enables the drive to clean itself up , you really need it. You may be better using your drive through the thunderbolt port its also faster than the USB3.
     
  7. chscag macrumors 68000

    Joined:
    Feb 17, 2008
    Location:
    Fort Worth, Texas
    #7
    Of course it's up to you to use an external drive, however, consider whether having your internal drive replaced with an SSD and having it done professionally would be better in the long haul. Perhaps more costly though. :)
     
  8. whcvip macrumors newbie

    whcvip

    Joined:
    Oct 29, 2015
    #8
    I can also recommend Sandisk Extreme 500, though I think max capacity is 480GB at this time. Have not tried the Samsung ones, but what I can read you have to install some software first to be able to use the drive at all, and like other have stated it is over priced. Have been using Sandisk Extreme 500 on my old 2013 iMac and now on my late 2015 5K iMac, runs well and fast enough I think, not to mention allot cheaper than what Apple charges for SSD drives.

    You lose TRIM and I get around 400MB/s write and 430MB/s read max, not bad at all compared to SATAIII drives, but compared to the Apple PCIe drives now at up to 1200MB/s you will lose some speed. Still though about 4 times faster than spinning harddrive, and my iMac feels snappy, on pair with my 2015 mackbook with 500GB PCIe SSD that even got faster read speeds.
     
  9. Weaselboy Moderator

    Weaselboy

    Staff Member

    Joined:
    Jan 23, 2005
    Location:
    California
    #9
    Not necessarily. Many people use external USB SSDs for ages and have no slowdown. If you are a particularly heavy user and the drive is near full, no TRIM can cause some slowdown in write speeds. But for most people under normal usage the built in garbage collection is able to keep the drive speed up just fine.

    There is very little difference in speeds between a USB3 and TB external SSD. Certainly IMO not worth the large cost increase for most people.
     
  10. stuartak macrumors member

    stuartak

    Joined:
    Feb 21, 2016
    #10
    You dont lose TRIM if you install a different SSD than as installed by APPLE you just have to enable it through Terminal, any SSD can have trim enabled. Go into utilities:terminal and type the command I think the command is only available from Yosemite on ...

    sudo trimforce enable
    it will then ask for your password , come up with a warning message which it asks you to accept then enables trim.
    To disable
    sudo trimforce disable

    The only thing you need to remember is that you will lose TRIM if you reload the OSX , you need to re-enable it.
     
  11. whcvip macrumors newbie

    whcvip

    Joined:
    Oct 29, 2015
    #11
    Not supported over USB3 im afraid. But yes if you replace internal SATA drive, you can enable TRIM.
     
  12. Fishrrman macrumors G3

    Joined:
    Feb 20, 2009
    #12
    stuartak wrote:
    "Not supporting trim will eventually bite you , as the SSD will get slower , this will only start to be noticeable as it fills up the drive , overwriting previously written cells on an SSD slows it down , trim enables the drive to clean itself up , you really need it. You may be better using your drive through the thunderbolt port its also faster than the USB3"

    I take issue with this.

    I've been booting and running a late-2012 Mini using an SSD in an external USB3/SATA dock for more than three years now.
    I've used a few different SSDs as the "booter", the latest one for more than two years now, and I have -NEVER- noticed ANY "slowdown" at all from the lack of TRIM.

    The SSD runs as "good as new", literally.
    This is from reports generated via the BlackMagic utility.

    Of course, my experience is my own, only.
    The experiences of others may be different.
    But what I report is from actually having used a setup like this for several years.

    I sense that Stuart above has never actually USED an SSD in such a configuration.

    To the OP:
    If you want to start booting and running from an SSD mounted in an external USB3 enclosure, I predict that you will be VERY happy with the results.

    The process is cheap, easy, and you completely avoid the hazards that may be encountered when opening an iMac.

    One word of advice:
    MAKE SURE you get a USB3 enclosure (or dock, or adapter dongle) that is SPECIFICALLY STATED to support "UASP" (USB attached SCSI protocol). This is required for the enclosure support the highest speeds possible.
    BE CAREFUL -- not all enclosures sport this feature!
     

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