I'm going to buy a second disk for backup, the same size as my laptops. I want to mount it in a casing via usb and backup an entire hdd every soemtime. That's because I want the posibility to just switch drives in case of something goes wrong. I'm using Linux and obviously the right tool seems to be dd. The thing is that my laptop drive has a speed of around 50-70 MB/s and usb 2.0 is 57 MB/s. So to copy my 250GB disk should take me more than 1 hour if I'm lucky. I can't wait this much. I want some differential backup. I read one of JWZ articles. In it he gives more details for using rsync on Mac. He writes that there is possibility of making rsync'ed disk bootable.

So my question is: how to make rsync'ed hdd bootable under Linux or are there other 'quick backup' tools for Linux that would allow me to just swap drives? Or should I just stick to dd :( ?