Running Mac on External Hard Drive

Discussion in 'iMac' started by jamesr94, Mar 22, 2017.

  1. jamesr94 macrumors newbie

    Mar 22, 2017
    Hi there!

    My iMac was acting strangely the other night (and had been for a while) and like a fool, I thought turning on FileVault might help things (I have no idea why I thought that) but all it did was crash my system beyond salvation.

    I managed to load OSX onto a friend's external hard drive and recover most of my files, however, my iMac's 3TB internal hard drive is pretty much dead and needs repairing/replacing. As such, I'm running my iMac on my friend's external hard drive until the end of my current University semester.

    Going forward, however, I was wondering, which is more cost effective and efficient:

    1) Replacing my internal 3TB fusion drive with another one
    2) Buying my own external hard drive and permanently running my iMac from it

    I'm having trouble finding out exactly how much a 3tb fusion drive replacement will cost - but I'm assuming it certainly won't be cheap. In contrast, very large external hard drives seem to be extremely affordable. For instance, the Lacie Rugged Mini 4tb is only around £180.

    What would the performance differences be, if any, between an internal fusion drive and external hard drive, such as the one above?

    Would it be stable, fast, and reliable?

    Is it that some external hard drives are better/specifically built for running operating systems whilst others are better suited to file storage - or is a hard drive a hard drive and you can do what you like on it?

    As you can see, I don't really know much about hard drives at the moment, so would welcome all of your advice and suggestions.

    Thank you for your time and help.

    Kind Regards,
  2. MacUser2525 macrumors 68000


    Mar 17, 2007
    Doubt the internal SSD is dead so it would only be the cost of the mechanical spinning drive that would be needed if the SSD is still good. While your are it you may as well check it out to confirm that namely format/re-install to the SSD only on the machine. If it succeeds then you know only the spinner needs replacing and if you can live with external storage for your large files then you can run for now from the internal SSD.
  3. jamesr94 thread starter macrumors newbie

    Mar 22, 2017
    Thanks for your advice!

    In Disk Utility all I have is 'Fusion Drive > Macintosh HD' - so how do I differentiate between the SSD and HDD? and then how would I specifically isolate the SSD in order to install my OS onto it?

    Thanks again for your help

    Kind Regards,
  4. maflynn Moderator


    Staff Member

    May 3, 2009
  5. Fishrrman macrumors P6


    Feb 20, 2009
    My suggestions:

    1. SPLIT the fusion drive as maflynn suggests above.
    2. Re-initialize the internal SSD
    3. Get the internal SSD up-and-running with an OS install, get an account and apps onto it.
    4. TRY to salvage the internal HDD by re-initializing it. IF it won't re-initialize, consider it to be "failed" and just "leave it in place where it is".
    5. Buy an external USB3 HDD of sufficient capacity, plug it in, and use that as additional storage.

    This way, you keep the iMac going WITHOUT splitting it open. This is hazardous for the user to attempt himself, and can be expensive to have someone else "fix" it.
    And you'll STILL HAVE the luxury of SSD boot and run speeds.

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4 March 22, 2017