Extrernal HardDrive unusable.

Discussion in 'Mac Basics and Help' started by adamlbiscuit, Mar 26, 2009.

  1. adamlbiscuit macrumors regular

    Sep 22, 2008
    Hi all. What a frustrating past few hours its been!

    To sum up: My External HD is seemingly corrupt, so corrupt i can't even format it.

    The big explanation:

    I had an External HD that i used for backing up my files, however, i didn't do it through time machine, i just did it manually. However, i decided today that i would use time machine.

    So I formatted my hard drive, and put it into 2 partitions, one larger one and one smaller one. The larger one was for time machine, the smaller one was for continuing to do my manual backups.

    Hours later it was all fine, used time machine for the first time and felt so secure. However, after using time machine and seeing what its all about, i no longer saw a point to having a second partition for manually backed up data. Manually backing up stuff just defeats the point of time machine doesn't it?

    So, I thought that since i'd only got one backup i would just format the HD once again and partition it into one big drive, purely for time machine.

    What i did:

    I entered disk utility and clicked on the name of my external HD, then selected the 'partition' tab. From there I selected 'one partition' from the drop down menu. Then I named my new partition 'Time Machine' and selected 'apply.' It told me that it'd erase the 2 partitions i already had and that was fine with me. I hit ok.

    It begins to partition and after a few seconds I get an error saying something like 'File Formatting failed'

    So I try again, and its the same. So, I try to erase everything on the disk, but i can't because i get the same error, and now nearly every command i try to do on it ends in an error.

    So it seems to me like i have a wrecked external hard drive, and I can't format it either. I'm betting any money i've done something so wrong, because while i am good on the Mac itself, all this hard drive business always ends up going wrong because of some option i haven't clicked.
  2. Makosuke macrumors 603

    Aug 15, 2001
    The Cool Part of CA, USA
    It doesn't sound like you've done anything wrong, but clearly something's not working right. Don't rule out the possibility that there's something wrong with the drive itself and/or the case it's in that was exposed by the reformat, but hopefully it's just Disk Utility acting up.

    Before you do anything else, try rebooting the computer and power cycling the external drive--that'll at least rule out "weird random glitch" as a cause if it doesn't fix it.

    To double-check, you are clicking on the least-indented instance of the drive in Disk Utility, right? It will look something like "931GB GB Bridge" or some such model info/model number. The, as you did, in the Partition tab select "1 Partition" and under the options button make sure GUID Partition Table is selected (should be the best choice if you're using an Intel Mac). You could also try Apple Partition Map just to see if that makes any difference--it should work either way.

    You didn't say what brand/model external drive you have--if it's one that has some built-in functionality (say, one of the Maxtors with "instant backup" buttons) that could cause a problem like this.
  3. Cave Man macrumors 604

    Cave Man

    In the Partition tab, click on Options, then choose GUID partition table, then initialize the drive as HFS+ with journaling enabled.
  4. BlueRevolution macrumors 603


    Jul 26, 2004
    Montreal, QC
    You have to set the volume scheme to "1 partition" before the Options button becomes enabled.
  5. adamlbiscuit thread starter macrumors regular

    Sep 22, 2008
    hey thanks for the replies. I've managed to sort everything out.

    It was a very stupid mistake on my part. I was setting the file system to 'Macintosh Extended Journaled' Now I thought this was correct since I was on mac, but when looking at the manual for the external HD it says it needs to be set to the MSDOS FAT file system. Since then i've been successful in setting up time machine (though odly when I selected the drive to use as a time machine drive, time machine said it had to reformat it. Normal or not?) and using it as a backup drive.
  6. Cave Man macrumors 604

    Cave Man

    I think you're asking for trouble down the road.

    This is likely because the drive was initialized at the factory with a master boot record, instead of GUID. The trouble that you might have is that FAT32 is limited to 4 gb file sizes. If you ever get into high-def movies (or even some DVD transcodes and disc images), those can easily get over 4 gb. I have several that are over 20 gb. I strongly suggest you try to reinitialize the drive with GUID partition table and HFS+ for journaling.

    Yes, TM is expecting an HFS+ volume.
  7. adamlbiscuit thread starter macrumors regular

    Sep 22, 2008
    the thing is i'm confused because when i click on the drive and choose 'get info' it says that its not MSDOS FAT anymore, but rather 'Mac OS extended - case sensitive'
  8. Cave Man macrumors 604

    Cave Man

    That's because TM requires HFS+, which is why you got that message in the first place.

    We've told you how to overcome this issue, so just do it. It's the only way it will work for your situation.
  9. adamlbiscuit thread starter macrumors regular

    Sep 22, 2008
    ok then so, this is how i'll do it:

    Open Disk utility, and erase the current volume
    create a new one making sure to have the GUID partition table and initialize it with HFS + The only thing is, there doesn't seem to be such an option, i'm looking everywhere and can't see it. I am a noob at these things and i might test your patience but please try and bear with me. Does HFS stand for anything?

    these are the options available, I may be looking in the wrong place



    I just looked up HFS + and it says its also referred to as Mac os Extended, is this the one i should use? Or is this info i looked up wrong?
  10. Cave Man macrumors 604

    Cave Man

    What you have checked, Mac OS X Extended (Journaled), is correct. That gives you HFS+.

    At the bottom of your screen shot is a button labeled "Options..." Click that to set GUID.
  11. adamlbiscuit thread starter macrumors regular

    Sep 22, 2008
    Right, done it! Thanks :)

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