Backup software with local data loss prevention (on not always on-line devices)

Question

I am looking for a backup software that will allow me to backup to a remote server, and automatically keep not synchronized local changes on a second storage medium (like a flash memory card), so that even if the hard drive crashes no data will be lost as using the second storage medium and the remote backup will allow me to restore up to the last point.

What backup software has this feature?

Answer 1

If you have a storage medium big enough to contain all your data (like an external HD), you can use Unison to sync Server <-> Computer <-> Device. You can set it to run silently and at the frequency you want. Unison is pretty safe and it does the right thing in corner cases.

If you want to store just the canged files in a small pendrive, I don't know of a software but there are hand-made solutions. You can hack with find and rsync to incrementally record recently changed files, and set a cron job to make it automatic. When your pendrive becomes full, just sync with the online backup and delete everything... the next automatic rsync will do the job for you.