Inconsistency between sum of folder sizes and start-up disk size

Use something like OmniDiskSweeper (free download)
<http://www.macupdate.com/info.php/id/7402/omnidisksweeper>

to find where your disk space is.

NOTE:
DO NOT touch /var/vm files
DO NOT touch /System/... files
DO NOT touch /Library/... files
DO NOT touch /bin/... files
DO NOT touch /sbin/... files
DO NOT touch /usr/bin/... files

If you do not find your missing storage under /Users/yourShortName/..., then one candidate is /var/log

It's hidden, so click on Desktop, select Go->Go to Folder->/var and click enter key. I suspect, just a WAG, that you might have ghost volumes. Launch the Terminal app in Utilities, copy & paste this command into the window that pops up, hit the return key, and post the results:

ls -al /Volumes/

Try /private/var/log, but based on your saying OmniDiskSweeper did not find the storage, I do not thing /private/var/log will be where it is hiding. OmniDiskSweeper would have found it, and showed /private as having a huge chunk of storage, but since you did not mention /private having the largest amount of storage, I do not thing /private/var/log is at fault.

While I think this is unlikely, if you have a very Very EXTREMELY large file that an application still has opened, but the file name has been deleted from the owning directory, then while it is still open, it will continue to consume storage until it is closed, but no utility will be able to find it.

I think this unlikely as you might have noticed such as file when you were creating it.

A reboot would force all open files to be closed, and any storage waiting to be deleted would be returned a free space. But again, I think you might have remembered creating such a huge file, so I'm not sure this is the answer. But a system reboot does not cost much.

Another possibility (maybe). Were you by any chance running Disk Utility -> Erase -> Erase Free Space... feature? The way the free space is erased, is that Disk Utility creates a mega huge file writing zeros to the file. Once Disk Utility has allocated all the free space on the disk, it is suppose to just delete the temporary file. If something went wrong with that procedure, it is possible that the temporary file is still hanging around as a lost file.

Recovering a lost file (one where the file meta-data and allocate storage still exists, but no directory entries point to the file can be found by booting from the Installation DVD, then going to the Utilities Menu and running Disk Utility -> First Aid -> Repair Disk. Any lost files will be placed in the /lost+found directory, and once the file has a directory entry OmniDiskSweeper will be able to find it.

Regardless of whether there is a lost file, if you have reached this stage and not found the missing storage, an Installation DVD -> Disk Utility -> First Aid -> Repair Disk is most likely called for.

PS. I hope you have been maintaining good backups (Time Machine or other), as when strange things start happening to a file system, you may be lucky and not loose anything, or you may have already lost something you wish you had back. Disk drives are mechanical devices and they can & do fail. Backups are your only real protection. Several different forms of backup if you really care about your data.

Message was edited by: BobHarris

You have a very large file or files which is invisible or is in an invisible folder.

1 ensure that your backup is up to date

2 reboot

3 check the Trash. There should be a now visible very large file or files there. Empty Trash.

4 find out what caused the very large file or files to be generated; typically this will be a runaway logfile or too many swapfiles.

If after rebooting you still have the problem, then you probably have a directory problem. Try

1 shut down all the way.

2 boot off your system disc.

3 run Disk Utility and repair disk.

4 reboot.

If this still doesn't solve the problem, repeat only using a heavy-duty disk utility, such as Disk Warrior, Drive Genius, or Tech Tool Pro. They can sometimes find problems that Disk Utility can't.

Alternatively, reformat the drive and restore from your backup, which might be faster. (You do have a current backup, don't you?)

If the problem isn't a runaway log, then he's almost certainly got severe directory damage, and if he doesn't have a good backup he's gonna lose stuff. This is especially so as ODS isn't finding anything. ODS should find large files, even invisible ones.

Another possibility is that OmniDisk Sweeper is not picking something up because it is not able to see items from another user account or certain parts of the system. Here's an excellent post from jsd2 which discusses how to get around this by enabling it to run as root.



+Re: Free space being reported incorrectly in 10.6.5+
+Posted: Dec 5, 2010 8:42 AM in response to: BocaBoy+


+I would run Disk Utility's Verify Disk, and if there are no problems reported, would continue to look for hidden items that are taking up the disk space.+

+There are folders on the HD that an admin user account doesn't have permission to access, and this means that apps such as OmniDiskSweeper that you run under your user account can't access these folders either. One example is the hidden top-level .Trashes folder, which is used only when you trash items on the HD when you are booted from elsewhere, and to empty it you need to be booted from elsewhere as well. Carbon Copy Cloner does not copy this folder. There are other possible restricted folders as well. Restricted folders will be reported as size zero even if they contain large files, and this will make the summary information incorrect as well.+

+To get around this restriction, you would need to examine the HD using "root" privileges. There are a number of ways to do this, but assuming that OmniDiskSweeper is currently in your main /Applications folder, you could try the following:+

+Open the Terminal (in /Applications/Utilities). Copy the following line and paste it directly into the Terminal window, then type Return:+

+sudo /Applications/OmniDiskSweeper.app/Contents/MacOS/OmniDiskSweeper+

+Enter your admin password when prompted (it will not echo on the screen), and type Return.+

+This should open OmniDiskSweeper's "Drive List" window. Click inside it and then sweep your HD as you did before. This time OmniDiskSweeper should run with "root" privileges - see what you get this way.+

i didn't think of other accounts. Yeah, the file or files could be inaccessible to ODS. DW etc should still fix the prob, though.