I have tried several backup solutions for my data and none of them was good enough.
I basically want to make a copy of my files to an attached USB Drive from time to time. I don't mind starting my backups manually, since the USB Drive is not always connected.
My problem is that my data contains a lot of files (a huge amount), so backing up takes forever (more than 20 hours).
Using "rsync" an other similar solutions is not working because the I/O needed to check the file for changes takes longer than the time to actually copy it.