How to resize and merge partitions on external HDD

Discussion in 'macOS Sierra (10.12)' started by OneZweiThree, Jan 5, 2017.

  1. OneZweiThree macrumors regular

    Joined:
    Feb 17, 2013
    Location:
    Bavaria
    #1
    Hey people,

    Im currently trying to re-partition my external HDD.
    Here is my current Setup:

    Partition A: 200GB (0 used)
    Partition B: 700GB ( 250 used)
    Partition C: 100GB (0 used)

    What i want to have:

    Partition A: 500GB
    Partition B: 500GB (without loosing the 250GB already used)

    Is this possibly at all, without using another HDD?
    Because currently, if i choose the external HDD in the Disk Utility, the partition button is greyed out and i cant click it.

    Thanks for your help!
     
  2. daflake macrumors 6502a

    Joined:
    Apr 8, 2008
    #2
    I would take a look at GParted (Google it) to see if it can do what you want. Is the external drive HFS+?
     
  3. OneZweiThree thread starter macrumors regular

    Joined:
    Feb 17, 2013
    Location:
    Bavaria
    #3
    I have actually no idea. It says macOS Extended (Journaled) on each partition, if thats what you are looking for?!
     
  4. daflake macrumors 6502a

    Joined:
    Apr 8, 2008
    #4

    Yep, but a little research just showed that GParted can't grow a partition of this nature.

    https://en.wikipedia.org/wiki/GParted

    What I would do is delete A and C (not being used) then shrink your B partition by 200. Then you could create a new partition of 500 and get what you are looking for. I still think you might need a 3rd party tool. Maybe someone else can chime in with some assistance as I have been off of Mac for a while now. What I suggested could easily be done in Windows and Linux.
     
  5. KALLT macrumors 601

    Joined:
    Sep 23, 2008
    #5
    Partitions can only grow or shrink at the top. In your case, you cannot get around deleting partitions.

    I suggest you resize partition B so that A and B have a combined size of 500 GB (you might be able to do this also by splitting partition B into B1 and B2, where your data resides on B1). Then you simply delete partition C (and B2), clone partition B (or B1) to partition C, then delete partitions A and B to create a new partition.

    This can be done with Disk Utility.

    You have to select the drive, not a partition. Only a drive can be partitioned.
     
  6. OneZweiThree thread starter macrumors regular

    Joined:
    Feb 17, 2013
    Location:
    Bavaria
    #6
    Thanks for your help. If it doesnt work on macOS, i can probably ask a friend, who uses Linux, to help me out.
    --- Post Merged, Jan 5, 2017 ---
    But even when i select the drive, the "partition" button stays greyed out. Do I need to do something else, before I can partition the drive?
     
  7. KALLT macrumors 601

    Joined:
    Sep 23, 2008
    #7
    Are all the disks mounted and unlocked?

    You can give us an overview of your setup with this Terminal command:
    Code:
    diskutil list
     
  8. OneZweiThree thread starter macrumors regular

    Joined:
    Feb 17, 2013
    Location:
    Bavaria
    #8
    here is a screenshot from the terminal:


    http://imgur.com/a/1ftrJ

    When i hover over the greyed out partition button, it says something like "master Boot record-drives can not be partitioned". (its in german for me, so i dont know the exact english wording)
    I guess, this is the problem then, right?
     
  9. KALLT macrumors 601

    Joined:
    Sep 23, 2008
    #9
    Master Boot Record is indeed supported only to a limited extent in Disk Utility. I think you may be able to achieve what you want with several Unix tools, particularly the fdisk command, but I have very little experience with that one and it is a pain to use. The best way would be to transfer the data to another drive and then set up the drive from scratch.

    Alternatively, a Linux system can indeed use GParted to help you out.
     
  10. Fishrrman macrumors G4

    Joined:
    Feb 20, 2009
    #10
    OP:

    If you really want to do this cleanly and reliably, there's one way that's guaranteed:

    1. Back up partition B to another drive (I recommend CarbonCopyCloner or SuperDuper)
    2. Re-initialize the drive
    3. Re-partition it as desired
    4. Use CCC (or SD) to "clone back" from the second drive to the first one.

    A little more work, but not really that much.
    This will work, 100%.
     
  11. FreakinEurekan macrumors 68040

    FreakinEurekan

    Joined:
    Sep 8, 2011
    Location:
    Eureka Springs, Arkansas
    #11
    Reminds me of one of those pegs-and-rings puzzles.

    Delete C, resize B to 300GB. Create new C of 500GB, copy data from B to C. Delete B, resize A to take up the empty space.
     
  12. OneZweiThree thread starter macrumors regular

    Joined:
    Feb 17, 2013
    Location:
    Bavaria
    #12
    Thanks for your help. I borrowed a second HDD from a friend and did it exactly that way. Worked perfectly.
     

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