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.
Presumably the backup routine is reading the complete contents of each file on the USB Drive in order to determine if the file has changed.
The way I would do this is to use something that can quickly exclude files which have the same size and timestamp on both source and destination. I am sure there are many programs that do this, the one I tend to use is Beyond Compare. It is not free but there is a trial version so you can test to see if it works.
Properly configured, it can quickly tell which files need to be backed-up using just a directory scan and those files are just copied across without reading the existing contents off the USB drive.
Is this on windows? If so, set the device for speed in device manager. However then you must do the remove hardware before removing it or you really will get problems.