Problem with external hard drive decryption

Discussion in 'OS X Yosemite (10.10)' started by bums, May 8, 2015.

  1. bums, May 8, 2015
    Last edited: May 8, 2015

    bums macrumors newbie

    May 8, 2015
    I have a "WD Elements" 2TB USB 3.0 external hard drive that I use on my mid-2012 Macbook Pro running Yosemite (10.10.3). I encrypted the external hard drive when I first got it by simply right clicking the disc image on the desktop and putting in a password. Recently I was using a computer at school and trying to drag files onto my drive but it wasn't working without the administrator password and I assumed this was because of the disc encryption so I right clicked my external drive on the desktop of the school computer and clicked "decrypt" and decrypted it I thought. It turns out all i had to do was change the permissions of certain folders on the drive while the drive was connected to a computer that I had the administrator password too... but anyways now that I'm finished with all of that I can't re-encrypt my hard drive because now when I have my hard drive connected to my personal macbook pro it says the hard drive is currently being decrypted. It's been like this for days. Any tips? I've tried verifying and repairing the drive in disk utility and I've also, while in disk utility, clicked "file->turn off encryption" and it doesn't do anything. I'm including a screen shot of what I see when I right click the external hard drive on my desktop. thanks in advanced for any help!

    edit: also worth noting, the hard drive is about 2/3 full, is it possible it's just taking this long to decrypt the entire drive and each time I connect the drive to the computer it's picking up where it has left off? I did't really think this type of encryption done in Finder was really doing much, I thought it was basically just a simple password protection. thanks

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  2. kagharaht macrumors 6502a

    Oct 7, 2007
    It takes awhile to decrypt. I remember a 2TB Decrypt took 4 days on a Macbook Pro 2008 Duo Core. Crazy yes, but it did finish after about 4 days. lol
  3. idoccurt macrumors regular

    Aug 25, 2006
    have you used file vault....worth it?
  4. bobr1952 macrumors 68020


    Jan 21, 2008
    Melbourne, FL
    I guess you are asking a separate question? I have encrypted my external drives and use Firevault on my Macbook Pro. There are many reasons to use Firevault and in reality, no downside for most people. I have never noticed a performance hit of any significance. And your login password cannot be bypassed if you have Firevault enabled. The only real downside is that you have to make very sure you don't forget your password--or lose the encryption key. I would recommend everyone enable Firevault.

    Oh--one comment on decrypting an external drive. My understanding is that with both encryption and decryption, the entire drive is done--not just the data on the drive--so it takes forever regardless of how much is actually stored on the drive.
  5. sjinsjca macrumors 68020


    Oct 30, 2008
    It will take a while to encrypt or decrypt a drive connected by USB. Every bit and byte of the drive has to go back and forth through that interface. At least, in Apple's implementation, it happens in the background and you're free to use the drive during the process.

    Let it do its job for however long it takes. It's a one-time thing.

    What isn't clear to me is if you are using Apple's encryption or some Western Digital functionality. Apple's encryption is FileVault2 and leverages an encryption engine built into recent Intel microprocessors (a functionality not present in previous Core 2 Duo and earlier processors, which can still do the job but will take longer).

    You might also ask why you're encrypting. Is there stuff on the drive that you don't want others to get-at if they should take possession of your drive? If so, then carry on. But it does add complication.
  6. kagharaht macrumors 6502a

    Oct 7, 2007
    Yes but you will definitely get a 10 to 20% hit on CPU processing speeds. Read/Write will slow down on HDD. From what I've read, not so much with SSD. This is from Lion. I haven't seen an updated report with Mavericks or Yosemite.

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