Does APFS Mean a Bigger SSD?


macrumors newbie
Original poster
Jan 3, 2011
Well, just as I was about to order a new 27" iMac (replacing my geriatric 2009 Mac Pro), I saw some stuff on the Apple Developers Forum that gave me pause about my configuration. I was going for a top flight configuration except I thought a 512 GB SSD would be big enough. My current MP has the same size SSD with only half used. I tend to archive documents and downloads to another disk, although admittedly haven't cleaned up in a long time. I could save another 100 GB if I were better about that.

Anyway, I recently saw some posts on the Developers Forum by people running the beta of HighSierra and there appears to be some problems with the APFS snapshots taking huge amounts of disk space. Now I know this is beta software and it could all be fixed before release, but it is making me re-think my choice of SSD size. What if even after getting the most serious bugs out of APFS it takes significantly more space. I could delay the purchase decision but I WANT MY NEW COMPUTER!

Any thoughts?


macrumors 603
Feb 13, 2012
Perth, Western Australia
IN theory, when it is done, APFS should require less space due to the single instance storage for copies.

512 GB is currently the sweet spot, if you need a lot more storage you're better off hooking it up via USB-C/Thunderbolt when you need it (at which point it will be cheaper and faster).


macrumors 68020
Sep 7, 2007
There's a great keynote that explains to developers how the apfs is going to be used, and how it saves space for data, by the way it writes and uses and allocates data.

It's not that the drives end up being bigger, or that you really save up more space. But if you make 10 copies of 10 gb files, you don't end up with 10x 10gb files. It will show just 10gb, until you start editing 1 of those copies (basically).