Time Machine - Troubleshooting

D7.  All  Backups  are  Full  Backups

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If it seems like every backup is a full one, first be sure that’s really true (sometimes it’s not easy to tell).  Don’t be misled by using the Finder to see the size of the dated backup folders;  that’s very misleading  (see How Time Machine works its Magic for an explanation).

Instead, check the copying "xxx GB of yyy GB" messages shown on the Time Machine Preferences window while a backup is running, and/or the log messages, per item #A1.  Compare those sizes to the Estimated size of full backup (Lion or Snow Leopard) or Included Items (Leopard) under the exclusions box in Time Machine Preferences > Options.

If those really show large, repeated backups, make sure there isn’t another explanation -- see sections #D3  and #D4 first.  Once you’re certain neither of those explains it, try a "full reset" of Time Machine, per item #A4.  That will usually fix it.

If it doesn’t, you need to figure out exactly what is getting backed-up repeatedly, since there are different causes, and each cause has a different fix.

Often, it’s a user’s home folder.  After doing the "full reset" per item #A4, try excluding one entire home folder from backups, via Time Machine Preferences > Options.  Click the plus sign at the bottom, then navigate to the home folder in question, select it, click the Exclude button, then the Done button on the main exclusions window.  Then run another backup.  If the "Copying xxx GB of yyy GB" message still indicates a full backup (nearly the size noted above), Time Machine really is trying to do a full backup, in spite of the exclusion list:  that’s usually caused by something corrupted in your installation of OSX.  You may need to install the "combo" update, per Installing the "combo" update and/or Reinstalling OSX.  If that doesn't help, you may want to reinstall OSX (that won't disturb anything else), per the same article.

If not, and the "Copying" message indicates a much smaller backup, there’s likely a problem with your home folder.  To confirm this, try another account’s home folder.  If you don’t have one, go to System Preferences > Users & Groups (or System Preferences > Accounts on Leopard or Snow Leopard) and create one.  With your main home folder still excluded, run a backup.  That should back up everything in the new user account’s home folder.  Then make a couple of small test files, in different sub-folders, such as Desktop and Documents, and run another backup.  See item #A2 for a couple of apps that will show exactly what was backed-up each time (but don’t try it on one of the really big ones, as it will take a very long time.)   If only the test files in the second home folder were backed-up the second time, then the original account and/or home folder is somehow corrupted.  See the pink box below.

Fixing a corrupted home folder doesn’t seem possible, unfortunately.  The only workaround is to create a new user account, copy the contents from the old home folder to the new one, then delete the old account and home folder.

See  Transferring files from one User Account to another for instructions.

You can copy sub-folders you created that way, but you can't copy the automatically-created and required "default" sub-folders, such as Desktop, Documents, Downloads, etc., that way.  You'll have to copy the sub-folders within those folders, so it will get rather tedious.  Be very careful -- it's easy to miss things in that process.

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