Although, I thought Dropbox kept a history on each file going back a month.....
I have a local Time Machine backup that is going continually. This allows me to quickly recover from most problems. However, if my house ever blew up, it wouldn't be sufficient, so in addition...
I have a Backblaze account. $5/month for everything on one computer, which is fine because Dropbox syncs my laptop to that computer. That backup runs continuously and keeps 30 days history (so if I delete a file and need to get it back, I can). Since I only care about disaster recovery here, if my house does blow up, they'll send me a hard drive with everything for around $100.
The combination means I feel pretty comfortable. I just hope my house doesn't blow up!
Once a month do a full image on both Windows and OSX systems. Save the images to another backup drive and take that backup to a safety deposit box at your bank.
If you want to be really paranoid, find a provider that offers fireproof storage for media. If you can't, go to your local storage facility and rent a small unit (maybe $30 to $75 per month, depending on where you live). Buy a fireproof safe and stick it in there. Once a month (or whatever) rotate drives through the safe.
You can also avoid the storage unit rental expense and locate a fire-proof safe at a trusted friend's or family members home or garage. Be creative.
In other words, creating a system that will virtually ensure the security of your data isn't hard or expensive --particularly when compared to the value of the data you are trying to protect.
On Windows you can get the same effect using VSS - http://en.wikipedia.org/wiki/Shadow_Copy
Also, since you seem to be knowledgeable about Linux, why do you use Dropbox at all, instead of just git or rsync or scp or whatever?
I used to use Mozy but when I tried a trial restore it was taking forever and missing some files. Also it inserts these .PART files into your system that can almost double the size of the folders you're trying to back up.
I looked at backblaze but it doesn't work with server computers.
So I'm now trying crashplan. I'm really interested in the feature of crashplan which allows automated backups to other computers. Only problem is that I've not been able to get this to work so far. Backing up to the cloud is working well though. Also its very competitively priced. I've yet to try a restore.
[1] though I'm switching off of them, not sure where to yet. There's some sort of issue in their client software that murders my home network, rendering the entire thing unusable while a backup is running. Their support was... less than helpful in trying to remedy the situation. For $5 a month and with the amount of stuff I was backing up, I can't blame them.
If you accidentally delete a file in Dropbox on one computer, Dropbox will helpfully and immediately propagate that deletion to all of your other computers. It can be used for backup, but it's not very good at it.
