Mac OS: Minimum and Maximum RAM Disk Size

This article lists the minimum and maximum RAM Disk sizes for various versions of Mac OS.

Mac OS Version
Minimum RAM Disk Size
Maximum RAM Disk Size
Notes
System 6 and earlier
192 K
256 MB
--
System 7.5.2, 7.6.x
416 K
256 MB
Maximum RAM Disk size is based on the amount of installed RAM minus the RAM required to run the system software.
Mac OS 8 and 9
512 K
256 MB
Minimum RAM Disk size is determined by amount of RAM in computer; 512 K for every 128 MB of RAM.
Maximum RAM Disk size varies by available RAM, but never exceeds 256 MB.

For additional RAM Disk information, see the following articles:

Article 16809: "RAM Disk: Description, Setup, and Use"

Article 16810: "RAM Disk: Resizing or Deleting"

Article 17699: "RAM Disk: Resetting the PRAM Causes Loss of RAM Disk Contents"

Article 58145: "Mac OS: Cannot Disable RAM Disk"

Published Date: Feb 20, 2012