Time Machine - Frequently Asked Questions
9. Why are my backups so large?
Time Machine - Frequently Asked Questions
9. Why are my backups so large?
There may be ways to minimize the size of such backups; search and/or post in the appropriate Apple forum for help:
One solution is to simply exclude the item from Time Machine so it isn't backed-up regularly, then when you do want it backed-up, just copy it somewhere that's not excluded. See question #10.
You can use the Time Tracker or BackupLoupe apps (see Troubleshooting item #A2) to see exactly what was copied on any particular backup.
A number of things can cause extra-large backups:
•Time Machine may be doing a full backup of your entire system. See Troubleshooting item #D3.
•Erasing a disk/partition that's excluded in Time Machine Preferences > Options will remove it from the exclusions box, so Time Machine will try to back it up.
•Doing an OSX update can cause a large backup, as it may add or update many thousands of files.
•Removing exclusions, such as your top-level System and/or Library folders, can be sizable.
•Renaming or moving a file or folder causes the entire item moved or renamed to be backed-up, including all files and sub-folders (except in a File Vault 1 home folder).
•Sometimes a corrupted preferences file can cause things to be backed-up that didn't actually change. Try a "full reset" of Time Machine, per Troubleshooting item #A4.
•If you use the ResetPassword facility to reset the permissions and ACLs on a user home folder, each item it actually changes will be backed-up on the next backup.
•There are some applications that can, in some circumstances, cause large backups. See Troubleshooting item #D8 for details.