Problems reformatting encrypted drive

Discussion in 'macOS' started by Astrophys, Aug 9, 2014.

  1. Astrophys macrumors newbie

    Aug 5, 2009
    I have an external 1TB Western Digital My Passport Studio hard drive that encrypted in disk utility. Due to the slow write speeds I reformatted the drive back to normal. The drive is still very very slow when writing. When I run verify or repair disk I keep getting errors. The drive also seems to be having a hard time unmounting when I try to reformat.

    Not sure what steps I can do to resolve this, and ideas?
  2. sjinsjca macrumors 68020


    Oct 30, 2008
    I presume you're attached via USB 2. That's a pretty severe bottleneck. FileVault, by comparison, has an almost unnoticeable impact on drive performance. USB 3 is better but, in my experience, still far short of a natively-connected drive. Thunderbolt is best, but then you might encounter the sad fact that external drives often have lousy controllers and stingy caches.

    You can try a different USB cable (they can have a profound difference) but it's likelier that this is just going to be a slow drive.
  3. Astrophys thread starter macrumors newbie

    Aug 5, 2009
    I'm using a Firewire 800, but it is no longer encrypted. I've read that there are some difficulties to reformatting an encrypted drive. I've had to go into the recovery start up to run disk utility, but still an unable to resolve the problem.
  4. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    Just so I am clear... you are now able to use Disk Util to erase the entire drive and after that when you verify the disk with Disk Util you see errors? That sounds like a failing drive.
  5. sjinsjca macrumors 68020


    Oct 30, 2008
    Well, FireWire 800 is maybe 2X faster than USB2, but still crimped compared to Thunderbolt or even USB 3. Drive operations will be slower, and some will be way slower (such as random access).

    Another thing to consider is the physical health of the drive. Do you have the same issue with other drives or just this one? It might be worth testing to see if you can isolate the issue to the drive itself. Drive death is a matter of when, not if.

    (I've not had difficulties reformatting my FileVault2-encrypted SSD, for what it's worth, not that I make a daily practice of it. But I've done it a couple times; long story.)

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