I use some USB 2.5" harddrives for offsite backups.
I have written a bash script (actually copied and adapted someone else's...) that create a "snapshot" of my calibre library. And the software use hard links to avoid storing duplicates of the same file on the drive, instead it just makes a hard link to files that are identical to one already stored. I have 4 generations of backups on each drive, and keep one drive away from home and swap once a week. I keep a copy of the script on each drive, so I attach the drive and run the script backup.sh that pops up.
The script is mainly based on rsync that is available for Windows, Linux and OSX. But I assume that there is some commercial software with similar capabilities? In OSX there is also the time machine.
Here is the brilliant original script I based my scripts on:
http://www.mikerubel.org/computers/r...hots/#Abstract
By jumping through some hoops it seem that this can be fully adapted to Windows, but I haven't tested it:
http://www.tomscott.com/barcamp2/
I also use the Linux software Back In Time, that also utilize rsync, to take automatic hourly full snapshots, without duplicate files, that are stored on a separate harddrive in the computer, and a daily snapshot that is stored on a NAS. Back In Time is set to automatically delete snapshots so I just have hourly snapshots for a day, daily snapshots for a week and weekly snapshots for a month. Monthly snapshots only gets deleted manually or when the backup disk is full. *