Home Forums Peripherals & Multimedia Peripherals How to resize partitions on external HD

The Problem:
My external hard drive will not allow me to repartition the top partition (there are 2 partitions). It is properly formatted for Mac.

I am able to make the lower block bigger, but I can not make the top block larger which is the goal.

Grabbing the resize point and dragging works for the bottom and not for the top where I need to use the extra space. I have tried resizing the smaller partition (successfully) to make the necessary room but the top partition is still giving me the bird.

I have also tried changing the numbers manually, at the end of repartitioning the top one defaults back to it's original size,

My computer is a Mid 2011 iMac 21.5" running Mavericks 10.9.5

Hi, and welcome to FineTunedMac.


Unless there's a 3rd party app that can turn the trick, it doesn't look very good for you. (I dunno... iPartition [$40]?)

You've just posted the precise reason many folks around here shy away from partitioning their disks...because the space you need is always on the other partition.

Artie is spot on as far as using Disk Utility goes but if you do find a tool that purports to work remember that in spite of the claims about non-destructive partition resizing wise users will always back up both partitions to another drive(s) before attempting to repartition. No one has repealed Murphy's Law yet and there is always a finite chance for error and so you do risk losing everything on both partitions when you repartition.


To piggyback on Artie's comment, if you feel it is essential to keep the contents of the two partitions separate you can do that on a single volume by creating two "Sparse Disk Images" or preferably "Sparse Bundle Disk Images" on the drive (the Sparse Bundle Disk Image is what Time Machine uses and gives better performance when there are a very large number of files). You don't increase the total drive capacity, but the images can expand or contract as needed and you do not have hard limits as you do with partitions.

I have to agree with Artie and Joe, but to return to your original query:

Question: which Partition Map Scheme did you use for the drive (listed bottom right in Disk Util window)? Anything other than GUID may affect resizability.

Apart from that, you may want to check if the situation described in the MacRumors thread I can't resize my 2nd partition on my MacBook Pro matches yours. If so, you can follow the road map described there to deal with the problem.

In all cases, however, your best bet is to back up your current HD to another one and then fix the problem one.

Have you tried to boot into recovery HD partition and resize partition from there? If any possible solution mentioned above is not fruitful.

Just to set the record straight - and offer The Dude a bit of positive reinforcement in the process - while I was waving the party flag, I'm not a party member.

I maintain four partitions on my MBP's 500GB HDD because they offer me great flexibility in terms of disk usage while hugely simplifying the process when I'm either forced or just inclined to do a clean install. (Details on request)

My habits, which may be decidedly different from those of others, make it pretty unlikely that I'll ever run out of space anywhere I need it, but in the event that I do, I'm fully backed up, and the time and effort savings I'll have banked by then will more than compensate.

Thank you everyone for the responses. I'm still reading into them all more, thanks again! Here is a bit more info as requested:

Format: Mac OS Extended (Journaled)
Write Status : Read/Write
Connection Type : External
S.M.A.R.T. Status: Not Supported
Partition Map Scheme : GUID Partition Table