The Secret to Reformatting a Western Digital WD 1TB My Book External Hard Drive

Posted on January 26, 2008 by Adam Nash

Little tidbit.

When you buy a Western Digital (WD) 1 TB My Book External Hard Drive, they usually come formatted for Windows using FAT32. Of course, if you are using it with a Mac, then you’ll want to reformat it using Mac OS Extended (HFS+).

The problem: When you try to reformat in Disk Utility, you’ll get a very cryptic error that says that there was an unknown error with the partition map.

The solution: If you go to the partition map and click the “Options…” button, you’ll be able to select which scheme to use for the boot records. It turns out, if the boot record scheme is set to “Master Boot Record”, you will not be able to format it as Mac OS Extended. Flipping it to GUID or Apple Partition Map will work.

Once you get to that magic dialog, it’s pretty clear what to do. Why Apple doesn’t communicate this error intelligibly when you attempt to format I don’t know.

In any case, there is an Apple Discussion Board thread that saved the day for me. I’m posting it here just in case it saves the day for someone else.

I’m now ready to try out Apple Time Machine for the first time…

Update (12/29/2008): It’s amazing, but this continues to be one of the most popular posts on this blog.  Everyone seems to have this problem.  Interestingly, it’s not unique to Western Digital drives.  I find that I need to do this with Maxtor and Seagate Free Agent drives also.  I just did this with the new Seagate FreeAgent 1.5 TB external.  Works like a charm…

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Filed under: Apple

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23 Responses

  1. jonny, on February 28th, 2008 at 3:54 pm Said:

    thanks, i love you!
    who woulda known that

    Reply
  2. jpwm, on May 27th, 2008 at 4:47 am Said:

    brilliant. simple.

    thank you.

    now to unleash the time machine!

    Reply
  3. Daphne, on August 6th, 2008 at 5:05 am Said:

    Thanks! I never would have thought of this, and it worked like a charm.

    daphne

    Reply
  4. Sim, on August 26th, 2008 at 10:49 am Said:

    Thanks, I just bought a Western Digital My Book Essential 500GB about 10 minutes ago on Amazon.co.uk and am currently using a Black MacBook running Tiger 10.4.11. Im hoping this post will prove very useful when the hard drive arrives and I get started using it as I have been warned by some other users about formatting problems regarding this external hard drive. I will bookmark this page and hopefully everything will be ok when it arrives. Thanks in advance.

    Reply
  5. Todd, on October 23rd, 2008 at 9:11 pm Said:

    Thanks alot, I had this same problem with a Buffalo TeraDrive and they had know idea what the problem was. Todd

    Reply
  6. Mark, on December 25th, 2008 at 12:13 pm Said:

    Thanks that is such a lifesaver. Spent ages working out what the problem was! Why apple decided to use such a cryptic error message I don’t know, and there is no mention of this issue on the WD website, for some reason unbeknown to me.

    Reply
  7. Pete W, on December 27th, 2008 at 10:35 pm Said:

    Adam,

    So MANY thanks, I can’t tell you how much hair I was about to pull out trying to format my 1Tb drive! Just bought it today, and was beginning to think I would have to take it back to the store.

    I too am looking forward to using Time Machine – hope it works OK now!

    Happy New Year to you – you’ve made my day!

    pete

    Reply
  8. MisterRon, on December 28th, 2008 at 3:13 pm Said:

    Wow! Am I glad I uncovered your tip. I just spent a whole day trying “zero out” and reformat an external 640 GB WD drive & I have a 1 TB WD drive awaiting putting in my Mac Pro (gotta take out a smaller one :) .

    Your simple tip reminds me of the old idea that you have to pay an expert a fortune to do two minutes work, because he spent many, many hours learning how to do that thing in two minutes.

    Thanks!

    Reply
  9. David, on December 29th, 2008 at 3:52 pm Said:

    Thanks for putting this tip out there. I figured it out myself last night, but the solution was more serendipitous than skill.

    I am guessing that WD doesn’t put this out there because they want to promote the extra crap demo software that comes with the drive.

    Reply
  10. victor, on January 3rd, 2009 at 8:54 pm Said:

    thank you so much! just spend a while trying to figure this out, and your solution worked perfectly! thanks again!!!

    Reply
  11. John, on January 20th, 2009 at 11:50 am Said:

    Thanks heaps. I would not have worked this out in a month of Sundays!

    Reply
  12. NealSega, on January 21st, 2009 at 6:48 pm Said:

    THANKS! I was about to return the drive…

    Reply
  13.   The Secret to Reformatting a Western Digital WD 1TB My Book External Hard Drive « Psychohistory by CRACKMAC.COM, on January 23rd, 2009 at 3:52 am Said:

    [...] The Secret to Reformatting a Western Digital WD 1TB My Book External Hard Drive « Psychohistory. [...]

    Reply
  14. Eric, on January 24th, 2009 at 6:51 am Said:

    Many thanks – 5 mins searching the web after 2 hours of zero progress with Disk Utility and my new terabyte drive is reformatted, and ready to use.

    Reply
  15. Mike Goitein, on February 28th, 2009 at 8:45 pm Said:

    Adam – Nailed it. Props to you, my intelligent friend. You’re a godsend to Mac geeks worldwide. Cheers!

    Reply
  16. Glen, on April 16th, 2009 at 1:45 am Said:

    Huzzah! Yes, it is a popular post – for a reason. It works! Thanks for posting this. And, just fyi – this was the first search engine result on Google when I was looking for a solution. And well worth it.

    Reply
  17. maxnepstad, on May 17th, 2009 at 7:25 pm Said:

    You’re a lifesaver, thank you!

    Reply
  18. kollektor, on June 16th, 2009 at 4:28 pm Said:

    Thanks, Adam. It might be simple but I never would have got there without this tip.

    Reply
  19. Juan Carlos Alicea, on July 3rd, 2009 at 1:58 am Said:

    It still works. Thanks.

    Reply
  20. motoyen, on September 21st, 2009 at 5:03 am Said:

    Thanks for the tip! Installing Snow Leopard tonight and couldn’t figure out why my external back up drive wasn’t mounting on the desk top. Was just about to take out back and shoot it before I found this tip.

    Reply
  21. Galen, on October 17th, 2009 at 2:08 pm Said:

    THANKS!!!!!

    Reply
  22. BiiPiiGii, on November 29th, 2009 at 12:49 am Said:

    Well, this simple yet incredibly effecting manor in reformatting such an investment has proven itself AWESOME. I thank you for writing this article, if it is okay with you; I’d actually like to write an article on this as well. Thank you.

    Reply
  23. R2, on December 3rd, 2009 at 10:13 pm Said:

    Thanks for making my night shorter!!! Doing a backup before I install Snow Leopard…Merry Christmas!

    Reply

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