My son's friend brought me a white Intel Macbook with his thesis work on it. It is running File Vault (he'd taken a research trip to Japan and properly encrypted the thing) and something is filling up his hard drive to the point it's complaining he's running out of space. I booted up off the Snow Leopard disk and it told me that he was down to just over 2 Gigs out of 160 Gigs. He backed up everything onto other external drives and then bombed his iTunes library and got it down to where it had over 50 Gigs free.
Anyway is it possible File Vault has a memory leak or something and is using up "a lot" more drive space? I've been looking out there to see if there are other possibilities (like back in OS 9 days) of things using up drive space.
Yes. This is a common problem with FileVault in 10.6 and earlier.
FileVault creates a special type of disk image (.dmg) file in the user's home directory. But here's the sneaky thing... When you add a file to a FileVault, the .dmg gets bigger. But if you delete a file in the FileVault, the .dmg does not get smaller...and new files you add don't use that empty space! The .dmg file just keeps growing and growing.
You can recover space in a FileVault from the Security preference pane, but you have to have enough empty space on the disk to hold the contents of the FileVault (it creates a new .dmg, copies everything to it, and deletes the old one, I believe). If you don't do this periodically, and your disk fills up to the point where there's not enough free space to condense the FileVault, then you can end up well and truly buggered.