How to avoid losing all my files when my Dropbox syncs to a compromised Dropbox account?

Solution 1:

Use SugarSync or SpiderOak to backup the same directory as dropbox.

Update 1/2017:
Plenty of options for other backup systems these days including self hosted ones like NextCloud.
Dropbox has an option for email notifications for new logins to alert you quicker to a problem.
Dropbox has 30 days un-delete if you can access the web interface. Pro has an option to extend that to one year.

Dropbox has added 2 factor auth to help prevent bad logins from ever happening in the first place.

There's also a number of hardware NAS solutions and external hard drives that can sync to dropbox, providing a number of ways - from an offline disk to a custom backup plan on a NAS to keep a snapshot of your files.

Solution 2:

Maybe do a cron job to cp -R or rsync your Dropbox folder with another on the same machine. It may take up twice as much space but will be much safer just in case your "Doomsday scenario" were to occur.

Solution 3:

If you don't mind the cost then you could backup to 2 places, one could be purely an online backup service along with drop-box.

This link could throw some light into alternate backup services.

And if you are real finicky about your backups, you could reserve and entire partition or a hard-drive to sync your matter locally, continuously and real time like what DropBox does. You can achieve this using Acronis True Image Home, or CrashPlan.

CrashPlan has a free version, but for continuous backup you need CrashPlan+ which a paid version.

CrashPlan+ offers continuous, real-time backup, stronger 448-bit encryption and web restore from CrashPlan Central.

Acronis has a 30 day evaluation period, but you need to pay for the software if you want to use it beyond the evaluation period.

Both these software also have an online storage option, naturally a paid for service though CrashPlan gives you this services free for 30 days.