What are these messages that I see in my Console Log??

22GB free is getting quite close to the point where you run out of space for Virtual Memory (swap files).

The actual amount required depends on how much physical memory (RAM) you have, and what applications you're running - movies, graphics and audio need most memory/swap space in general.

Depending on how the disc has been used previously, if that 22GB is not contiguous (i.e. it's fragmented) then warnings will start popping up sooner rather than later to say you're out of disc space.

If you're only running office programmes you may be safe down to about 5GB or so, but it's definitely time now to be considering reducing the amount of data on the drive, or moving to a larger HD. Certainly you need a backup in place on an external drive, preferably slightly larger than your current boot drive so it doesn't suffer the same problem.

Freeing space on your Mac OS X startup disk; http://www.thexlab.com/faqs/freeingspace.html

How to free up my disk space; http://www.macmaps.com/diskfull.html

Whether any of that has anything to do with the spotlight messages (MDS, mdworker) I'm not 100% certain, but given the audit message it seems likely.

Read this:

Using Activity Monitor to read System Memory and determine how much RAM is being used

Don't use any disk defraggers on a unix based file system. It is unnecessary.

Swap files have doubling algorithm in how much gets alloacted for them. The directory /var/vm is where these files reside (do not touch those files). I always recommend keeping at least 25GB for th entire OS. That's leaves approximately 15GB for the swap space and other space needed for the OS operation.

The 25GB is basically a ballpark figure. Probably 20GB to 25GB is ok. But 22GB from for everything, i.e., the OS and you is really not enough. Maybe you should read the following:

Where did my Disk Space go?

And run OmniDiskSweeper and see what taking up what space.

Michael Levin wrote:

- do I need to use something like DiskWarrior to rebuild the disk or a real "defrag" like DriveGenius? I thought OS X doesn't need actual defragmenting.

Just to reinforce X's notes - under normal circumstances, no defragging is needed - the OS will defrag smaller files on the fly anyway.

When working with very large files on a regular basis (like movie projects or serious audio stuff), it's possible to accumulate fragmention of free space rather than files, which can cause 'out of memory' error messages earlier than would otherwise be the case.

But even in that scenario, it's not so much a defrag you need as more disk space.

On a further note - never use third party tools to defrag. You already have the best method available; just reverse clone the latest backup.

Once again, though, that's just delaying the inevitable need for a bigger drive.