VM larger than available disk space??

Hi, Eric.

I don't see anything in your screen shot to indicate that 11 GB of Available (free) disk space to begin with, nor that you had 7GB of free disk space at the time of this exercise. Your screen shot shows you had 11.83 MB of free RAM at the time.

The VM Size will differ both between available disk space and the size of the VM swap files (located in the /private/var/vm directory) as not all VM that is allocated is actually in-use. See the man page for the vm_stat command.

Your available disk space will decrease as VM increases, due to increased use of VM swap files, primarily due to swapping-out pages that have been allocated, but again won't necessarily match the VM Size. For example, the applications you are running and other system overhead may require nearly 40 GB of VM — a "potential maximum" — but only 4 GB of disk space (11 GB free at start - 7 GB free at end = 4 GB) may be occupied by swap files at present.

If, however, your system's need for swap files consumes all the available disk space, you could run into problems, such as kernel panics. See my "Problems from insufficient RAM and free hard disk space" FAQ for additional details.

Good luck!

😉 Dr. Smoke
Author: Troubleshooting Mac® OS X

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OK, I see the "7.14 GB available" in the border of the Finder window that is overlayed by Activity Monitor. Fine. I answered your question nonetheless.

Next time, you might want to try a screen shot that shows all and only the relevant items you're discussing directly, e.g. the Get Info window for your hard drive next to the Activity Monitor window. It is unreasonable to expect someone to go digging through the screen shot with a jumble of overlaid windows. You could also add some annotations to the screen shot to highlight your points of discussion.

Good luck!

😉 Dr. Smoke
Author: Troubleshooting Mac® OS X

Virtual memory is not just swap files. Open files are often mapped into virtual memory. In particular, applications are included in VM. If an application must be moved out of RAM, it does not need to be copied into swap space since it is already on disk -- in the application file. (I mean the application code and resources themselves, not data memory the app is using.) When you load an application, the system notes where it is on disk, and uses that instead of swap space. Read-only files are often handled the same way. Virtual memory is usually much larger than swap space+RAM.

OS X has always "allocated" virtual memory, even if it never physically uses it.

I just booted my system which has 1.8GB RAM
One swap file

According to Activity Monitor:
kernel_task is using 69MB Real Memory and 1.22GB Virtual Memory

A lot of times "VM" never goes to disk and is just, well, potential address space.

Still, you might consider upgrading RAM, and look into why you have so little free space, and do a couple backups, and off load some files. Your system should run better if the system is on and isolated to the outer tracks/partition and has more free space.