Time Machine backups are bigger than expected

Question

Hi everyone,
I was wondering if anyone would know why, all of a sudden after a day or two ago, my Time Machine is suddenly insisting on backing up well over 4GB at a time? Before then my backups would almost always be below the 100MB mark. Has some update happened that would have caused this?
I have looked in Console but unfortunately am none the wiser. Is there some way of finding out a list of the files Time Machine is actually backing up? If so then I'd be able to track down this problem since I am fast running out of space on my Time Machine backup drive!
Many thanks for listening...
:-Joe

Answer 1

Jowie,
Consider the following info that I have gleaned, some of it may explain some it.
*Incremental Backups Seem Too Large!*
Time Machine performs backups at the file level. If a single bit in a large file is changed, the WHOLE file is backed up again. This is a problem for programs that save data to monolithic virtual disk files that are modified frequently. These include Parallels, VMware Fusion, Aperture vaults, or the databases that Entourage and Thunderbird create. These should be excluded from backup using the Time Machine Preference Exclusion list. You will, however, need to backup these files manually to another external disk.
One poster observed regarding Photoshop: “If you find yourself working with large files, you may discover that TM is suddenly backing up your scratch disk's temp files. This is useless, find out how to exclude these (I'm not actually sure here). Alternatively, turn off TM whilst you work in Photoshop.” (http://discussions.apple.com/thread.jspa?threadID=1209412)
If you do a lot of movie editing, unless these files are excluded, expect Time Machine to treat revised versions of a single movie as entirely new files.
If you frequently download software or video files that you only expect to keep for a short time, consider excluding the folder these are stored in from Time Machine backups.
Files or folders that are simply moved or renamed are counted as NEW files or folders. If you rename any file or folder, Time Machine will back up the ENTIRE file or folder again no matter how big or small it is.
George Schreyer may be describing what you are experiencing: “If you should want to do some massive rearrangement of your disk, Time Machine will interpret the rearranged files as new files and back them up again in their new locations. Just renaming a folder will cause this to happen. This is OK if you've got lots of room on your backup disk. Eventually, Time Machine will thin those backups and the space consumed will be recovered. However, if you really want recover the space in the backup volume immediately, you can. To do this, bring a Finder window to the front and then click the Time Machine icon on the dock. This will activate the Time Machine user interface. Navigate back in time to where the old stuff exists and select it. Then pull down the "action" menu (the gear thing) and select "delete all backups" and the older stuff vanishes.” (http://www.girr.org/mac_stuff/backups.html)
*FileVault / Boot Camp / iDisk Syncing*
Note: Leopard has changed the way it deals with FileVault disk images, so it is not necessary to exclude your Home folder it you have FileVault activated. Additionally, Time Machine ignores Boot Camp partitions as the manner in which they are formatted is incompatible. Finally, if you have your iDisk Synced to your desktop, it is not necessary to exclude the disk image file it creates as that has been changed to a sparsebundle as well in Leopard.