I bought a new hard drive and now had to transfer the data from hard drive 1 to hard drive 2. I did not want to do this using dd, but instead copy directly through the filesystem. So I quickly booted a Linux Live CD and tried to copy my files using cp -a QUELLE ZIEL in the directly booted filesystem. However, I had not expected performance like that. rsync was not much good either.
Things went better with tar.
Copying files quickly using tar
cd QUELLE tar cf - . | (cd ZIEL; tar xvf -)
The downside of this solution, however, is that if it is interrupted, you have to start again from the beginning. But in that situation, rsync would again be the tool of choice for copying the files that are still missing.