FileVault size not compacting

Question

I've searched these forums for help with my situation and tried the hdituil suggestions but, so far, nothing has worked.
I'll give you the short version: I copied our music and photo libraries to our laptop internal drive so we could have them with us. Originally, I copied them to my user account but eventually realized that other users could not access it. Since I had only 40GB left on the internal HD, I had to use an external drive to complete the operation. I created an encrypted sparse bundle disk image on an external drive and copied the libraries to it. Then, I deleted the libraries from my section, logged out and back in to reclaim the space. I got most of the space back but not the entire 300GB (which was the size of the libraries). At the time, I thought nothing of it.
So I did some digging. According to What Size (UI for Unix command du), the two FileVault-ed account (disk image) files take up 127GB and 1.07GB respectively. Selecting all the files in each home folder, the disk image taking up 127GB is actually using 100GB. The account whose disk image is taking up 1.07GB is actually using 571MB.
Then, to be sneaky, I logged into the root account to attempt to compact them. When I did this, via Terminal, I got the following results:
For my disk image, it said: Reclaimed 3.8 MB out of 366.1 GB possible.
For my wife's disk image, it said: Reclaimed 0 bytes out of 464.2 GB possible.
Ok. So I found a post a week ago that gave instructions on how to reclaim the "missing" space. It mentioned needing Drive Genius 3 to accomplish this. Now that I actually want to read it, I can't find it.
Can anyone help? An idea what this means? Why doesn't the compacting that goes on when you log out of your account not reclaim all that space? It seems I could have an extra 28GB of space.
Thoughts or experiences? Thanks!

Answer 1

Welcome to Apple Discussions,
Apple's implementation of the FileVault sparsebundle's image apparently results in this peculiar observation - See this thread:
http://discussions.apple.com/thread.jspa?threadID=2227841
The apparent volume size of a mounted sparsebundle image is a "potential" size, which can be much larger than the current HD space occupied by the sparsebundle (hence the "sparse" in the name). Apparently the potential volume capacity of the mounted image can even be set larger than the HD itself, though it could obviously never be filled to that capacity by files because the sparsebundle could not grow large enough to hold them. What is also unusual in FileVault is that apparently a large fraction of the image capacity gets marked as "used" even before any files have been added to it, as described in the link above.
I guess the bottom line is that when you GetInfo directly on a FileVault Home (which is the mounted image), the "capacity" will be a number twice the size of the HD, the "available" number is probably accurate, and the "used" number is not meaningful because it reflects more than just the contained files.
If do want to see the size of the contained files, you could open a Finder window into the FileVault Home (showing the Documents, Music, Pictures folders, etc), and then type Command-A followed by Command-option-I. You will get an "Inspector" window which should show the total space used by the files, excluding the Trash.