Dropbox and Time Machine are not talking – UPDATED
Using Time Machine is a breeze – it’s backs up everything mac perfectly. But if you use dropbox you’re probably noticing your hard disk is rapidly filling on it’s own volition even though you exclude this from the Time Machine backup. (my dropbox weighs in at 30GB)
Even after doing this exclusion via the Time Machine System Pane it will still backup a hidden Dropbox cache database that increases with every dropbox change you make. This cache includes all those files you ‘thought’ you deleted and consquently Time Machine will backup huge files every hour. My hidden cache is an unnecessary 1.5GB, which was backed up every hour!
It’s kept hidden in your user folder <your home folder>/Dropbox/.dropbox.cache
How to exclude the hidden folder
Do this by using the “options” button in the Time Machine system preference pane.
1 – Click the add icon
2 – Check the ‘show invisible files’ checkbox
3 – Select the “.dropbox” folder in your home folder
4 – Confim by clicking Exclude
And you’ll notice backups taking less time straight away. Mine dropped from 1.5GB to 46MB.
View hidden files in the future by reading this post.
In recent builds of the Dropbox client it seems to be smarter about cache management, and the cache now appears to be kept in ~/Dropbox/.dropbox.cache so you don’t need a separate exclusion.
However you might want to recover disk space on your Time Machine volume by purging the old backups of ~/.dropbox/dropbox.db — `cd ~/.dropbox && open .` in Terminal to quickly get a Finder window, open Time Machine, and then see this tip for an illustration of purging all past backups of a file:
http://db.tidbits.com/article/9597
I went back to December 2010 to find a copy of ~/.dropbox/dropbox.db