Remove Partition and Keep Data

Discussion in 'macOS' started by FSMBP, Feb 21, 2009.

  1. FSMBP macrumors 68020


    Jan 22, 2009
    Hey, I tried searching the boards already but I didn't get a clear answer I was looking for.

    So I have an external harddrive with data already on (it takes up only 40% of the harddrive). Now, I want to partition the harddrive and use the new partition for a Time Machine backup of my Mac.

    Now, here's the question; would I be able to delete the Time Machine partition in the future and still leave the external harddrive's data (the original 40% of data I had in the first partition?

    I'd appreciate any help. Thank you.
  2. sickmacdoc macrumors 68020


    Jun 14, 2008
    New Hampshire
    OK- this is pretty easy to handle but it does come with a major IF which could prevent it.;)

    • IF your drive is currently formatted as Mac OS Extended with an appropriate type of partition map scheme (either GUID or APM) as opposed the PC fomatting most drives come with then you can do it.

    • If it currently has a PC type partiton map (MBR) you will not be able to add/delete partitions on your Mac. That would require moving the existing data off the drive and reformatting the disk to install the correct partition map type to allow for partition modifications later.

    SO- If your disk is currently formatted correctly, what you are asking is pretty easy- start Disk Utility and click the Partition tab. In the map that shows the partitons (or in this the case shows the single partition currently), there will be a "drag handle" at the bottom right of the existing partition. Drag that upwards until the partition is the size you want it to be. Make sure that the new size is not smaller than the amount of data you currently have on the drive. If you pick a size too small, the process will fail later on.

    Once you have dragged to the new size, the newly freed space will be a grey block at the bottom of the partition map. Use the "+" sign at the bottom left of the window. A new 2nd partition will be created out of the grey free space. Click on the new partition, give it whatever name you want and select Mac OS Extended (Journaled). Remember the name as this will be your new TM partition. It is important that it be the second partition to allow for it be removed later with no effect on the contents of the first partition.

    Make sure that at NO point in this should you change the "Volume Scheme" pulldown menu at the top yourself!! That would wipe the drive totally.

    OK now click Apply and you will presented with a summary screen of what is about to be done. It should note that the existing partition will be resized and not erased, and that another partition with whatever name you gave it will be created. Click continue and sit back for a short time and you should see two drive icons appear on your desktop.

    Depending on how many, if any, files need to be moved in order for the system to shrink the existing partition this can take awhile.

    And finally, the usual cautions apply: doing this without having a current backup of the data on the drive is not recommended. This procedure can go perfectly 100 times in a row, or it might glitch the first time you do it!;)
  3. FSMBP thread starter macrumors 68020


    Jan 22, 2009
    Thank you, I appreciate it! (I had to reformat my drive because it was a FAT 32)

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