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Creating RAM disk in macOS

Built-in

diskutil erasevolume HFS+ 'RAM Disk' `hdiutil attach -nobrowse -nomount ram://XXXXX`

where XXXXX is the size of the RAM disk in terms of memory blocks.

Notes:

$2048$ memory blocks correspond to 1MB. Thus, XXXXX = YYYY * 2048 where YYYY is the size in MB.

E.g.

  • ram://2048 will create 1MB RAM disk
  • ram://2097152 --> 1 GB
  • ram://4194304 --> 2 GB
  • ram://8388608 --> 4 GB

Third-party Tools

  • TmpDisk:: Open Source RAM disk management app.
  • Ultra RAM Disk installs as a menu bar item that allows you to create RAM disks when needed.
  • RAMDisk: is an app for creating as well as backing up RAM disks, to allow you to save their contents as well as restore RAM disks when you restart your Mac.
  • RAMDiskCreator

Resources

@hangtwenty
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hangtwenty commented Mar 2, 2021

Update in 2021: it seems that TmpDisk is the only GUI option now. At least, for me.

@kvaDrug
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kvaDrug commented Aug 14, 2021

In order to unmount such disk I use diskutil unmount /dev/rdisk3 then diskutil unmountDisk /dev/disk3. Is this a correct way?

@boatcoder
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boatcoder commented Sep 4, 2021

@kvaDrug. hdiutil detach /dev/disk2 works for me

@productdevbook
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productdevbook commented Sep 19, 2021

@kvaDrug. hdiutil detach /dev/disk2 works for me

diskutil erasevolume HFS+ 'RAM Disk' disk0 `hdiutil detach /dev/disk0 -nobrowse -nomount ram://33554415`

thats true ?

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