1 Reply Latest reply: May 12, 2011 3:34 PM by Bill Myers
Bill Myers Level 1 Level 1

geez, I hate writing a question when I think I've already found the answer!!

But in this case, the answer's so baad, I thought I'd run it by you all before I hit "desperation" mode! Here goes...


I've got a USB 1TB external that I back up on to. It's in 4 partitions (audio, video, system, archives). The 4 partions are using about 750 Gb total, with 250 Gb free. I wanted to resize the "system" partition, as it was getting pretty full. I found some instructions about; (1.) creating a new, fifth, empty partition out of that 250Gb free space then (2.) "merging" the new partition and the system partition, resulting in a single larger partion for system backups. All other partitions *should* have been left untouched.


I was a bit wary of it all, but Disk Utility's Help says, "You may be able to create multiple partitions on your disk without losing any data" and then goes on to tell me how to, using the + sign, create a  new partition out of the 250Gb of free space.

I followed the instructions to the letter but, after "Applying", it did create the new fifth partition, *BUT IT WIPED ALL OF THE DATA OFF OF THE OTHER FOUR PARTITIONS!!*


I'm in major panic mode, did a bit of searching and, on Indiana Univ. help page, found:

"Warning: ...when changing the partition scheme in Mac OS X 10.5 and later, partitioning your hard drive with Disk Utility erases all the information on the drive."

As I see it, a direct conflict to what Apple claims in Disk Utility's Help.


So, I'm about to pull out and upgrade my data recovery programs - - will just try and get the pix and tunes back, I guess.


But if anyone has any idea how I can "undo" what's been done, it sure would help!!


many thanks in advance,

b myers

MacBook Pro, Mac OS X (10.6.7)
  • Kappy Level 10 Level 10

    I'm not sure what you did exactly, but having done it you cannot undo it.   You may yet be able  to recover files from the drive using recovery software:


    Basics of File Recovery


    Files in Trash


    If you simply put files in the Trash you can restore them by opening the Trash (left-click on the Trash icon) and drag the files from the Trash to your Desktop or other desired location.  OS X also provides a short-cut to undo the last item moved to the Trash -press COMMAND-Z.


    If you empty the Trash the files are gone. If a program does an immediate delete rather than moving files to the Trash, then the files are gone.  Recovery is possible but you must not allow any additional writes to the hard drive - shut it down. When files are deleted only the directory entries, not the files themselves, is modified. The space occupied by the files has been returned to the system as available for storage, but the files are still on the drive. Writing to the drive will then eventually overwrite the space once occupied by the deleted files in which case the files are lost permanently. Also if you save a file over an existing file of the same name, then the old file is overwritten and cannot be recovered.


    General File Recovery


    If you stop using the drive it's possible to recover deleted files that have not been overwritten by using recovery software such as Data Rescue II, File Salvage or TechTool Pro.  Each of the preceding come on bootable CDs to enable usage without risk of writing more data to the hard drive.  Two free alternatives are Disk Drill and TestDisk.  Look for them and demos at MacUpdate or CNET Downloads.


    The longer the hard drive remains in use and data are written to it, the greater the risk your deleted files will be overwritten.


    Also visit The XLab FAQs and read the FAQ on Data Recovery.


    For future reference:


    To resize the drive do the following:


    1. Open Disk Utility and select the drive entry (mfgr.'s ID and size) from the left side list.


    2. Click on the Partition tab in the DU main window. You should see the graphical sizing window showing the existing partitions. A portion may appear as a blue rectangle representing the used space on a partition.


    3. In the lower right corner of the sizing rectangle for each partition is a resizing gadget. Select it with the mouse and move the bottom of the rectangle upwards until you have reduced the existing partition enough to create the desired new volume's size. The space below the resized partition will appear gray. Click on the Apply button and wait until the process has completed.  (Note: You can only make a partition smaller in order to create new free space.)


    4. Click on the [+] button below the sizing window to add a new partition in the gray space you freed up. Give the new volume a name, if you wish, then click on the Apply button. Wait until the process has completed.


    You should now have a new volume on the drive.