Changing partition sizes nondestructively?

Discussion in 'macOS' started by jent, Mar 21, 2012.

  1. jent macrumors 6502a


    Mar 31, 2010
    I have a friend with an external hard drive, who's formatted half for PC and half for Mac. She barely uses the PC side and wants to free up a lot of that for the Mac partition. She doesn't have the info on the external drive backed up, so I was wondering if it's possible in Snow Leopard or Lion to nondestructively repartition a hard drive, keeping the data on both partitions while still changing the size of each. Can it be done if all of the partitions are Mac OS X Extended (Journaled)? What if one is Mac OS X Extended (Journaled) and the other is MS-FAT? Thanks!
  2. r0k macrumors 68040


    Mar 3, 2008
    Read the following but don't do it yet...
    In disk utility, you can drag the lower right corner of a partition to resize it. This works great to reduce the size or if the rest of the drive is empty, it works for increasing size. In your friend's situation, I would suggest he back up the msdos stuff by copying it over to a folder on the HFS+ Journaled side. He can then delete the msdos partition. Once it shows up as free space, he can resize the HFS+ partition. Lastly, he can create a new msdos partition and copy the stuff there he saved in a folder on the HFS+ side.

    Now read this part and back your stuff up first...
    Ok what I said above will probably work. But what if something goes wrong? Your friend should have everything backed up. Everything. A second usb drive costs something like fifty bucks and you can get them at Target. It's not like you have to mail order from newegg and sign for a package. Tell your friend to go down to the store and get a second USB drive to act as a backup before he changes anything.

    Should everything get wiped? No. Will everything get wiped? Possibly yes. I know from experience that sometimes stuff goes wrong. On my wife's machine, I was installing Lion and something went wrong and her HDD suddenly showed up empty. I wound up reinstalling the OS and when I tried to restore from a Time Machine backup it was corrupted. All her stuff seemed to be gone. Luckily I had recently installed and paid for a crashplan subscription and it had made a copy on crashplan's backup server of her home folder which was all I needed. Whew!

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