If you use Time Machine to back up your Mac, you have the security of automatic backups. And if you’re a Dropbox user, everything in your Dropbox folder benefits from both the protection of offsite storage and file versioning. But what may not have occurred to you is that, by default, Time Machine is also backing up the contents of your Dropbox folder.
It’s important to realize that one of the key aspects of how Dropbox works is that it creates a Dropbox folder in your home folder and then syncs the contents of that folder with the Dropbox Web site. Move a file into the Dropbox folder and it’s copied to the Dropbox Web site; make a change, and that change automatically propagates to the Dropbox site. Because there’s nothing special about the Dropbox folder itself, it’s part of Time Machine’s backup set by default.
On the one hand, backing up your Dropbox folder with Time Machine gives you an added layer of confidence that your files in Dropbox are backed up locally, in case something were to go wrong with the Dropbox Web site. Plus, Dropbox maintains deleted files for only 30 days unless you pay for a Dropbox Pro account and enable the Packrat add-on in your account settings, so a Time Machine backup could let you restore deleted files after that 30-day period.
On the other hand, since all those files in your Dropbox folder are duplicated on the Dropbox Web site, they can be restored easily in case of accidental deletion or hard drive death, so there’s no inherent need to use space on these files on your Time Machine drive. (An earlier version of this article said that only files, not entire folders, could be restored from Dropbox. In fact, both files and folders, plus application packages, can be restored easily.)
To exclude your Dropbox files from your Time Machine backup, open the Time Machine pane of System Preferences and click the Options button to reveal the “Exclude these Items from Backups” dialog. Drag your Dropbox folder from the Finder into that list, or click the plus sign at the bottom and select the Dropbox folder in your home folder. Click Save when you’re done.
When I initially discovered my Dropbox files on my Time Machine backup, my first reaction was to exclude the files from my backup. After more thought, though, I realized there already had been times that I had deleted files from my Dropbox folder that I could have rescued via Time Machine. But if you have a Dropbox Pro account with Packrat enabled, or simply aren’t worried about needing to restore a deleted file more than 30 days later, you might prefer to save some space on your Time Machine
[Alicia Katz Pollock has been working with computers since designing a database on an Apple IIc for her father’s dental practice when she was 13. Today she is a consultant at Royalwise Solutions and a course author for Lynda.com. She holds a variety of Apple, Microsoft, and Intuit certifications.]