That is: a file system designed specifically for ramdisks? I know I could use any old file system but I want something specialized for performance.

  • 2
    Possible duplicate of superuser.com/questions/121989/… Jul 13, 2012 at 18:14
  • Not a duplicate: I am looking for an optimized file system - that question just uses HFS+
    – Ramon
    Jul 13, 2012 at 19:28
  • It's unclear what you define as "an optimized file system".
    – poige
    Mar 24, 2016 at 17:53

3 Answers 3


Short answer: no, there's no Tmpfs for Mac OS X. Tinkering with RAM-disks in Mac OS X is just naively mimicking what you get with Linux Tmpfs if you consider Linux' version as archetype — simply due to Tmpfs doesn't cut specified amount of RAM from system memory, allowing to swappage out its least-recently-used pages to swap.

Long answer is the same. ;)

  • I didn’t find any existing solution, but maybe we can write one with FUSE? Apr 14, 2020 at 5:54
  • > Tmpfs doesn't cut specified amount of RAM from system memory You can specify the size in mount Aug 3, 2021 at 16:42
  • @interoception Linux' tmpfs' size parameter is the maximum size. What they meant is that it doesn't cut out a fixed amount but grows with usage.
    – Atemu
    Mar 7 at 11:56

Once you have a ram disk device, you can put any fs on it you like. HFS+ is going to be at least within an order of magnitude as good as any other fs. Since you're on a Mac, it's the most natural FS to put on your ram disk.

But as stated in the other (duplicate) question's answer: unix is pretty darn good at caching files with memory it's not using for other things. Taking space away from your OS and dedicating it to a ramdisk is usually not a good plan.

If you want to lower your i/o wait times and you have a very specific need, perhaps add an SSD to your system and use that.

Without knowing the details of your performance needs, it's very hard to answer your question with specifics.


There are couple of FUSE implementations, which should work on Mac:

It seems you can also use hdiutil:

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