I attempted to copy contents of one partition to another using
cp -R /media/richard/myrepo /media/richard/test
/media/richard/myrepo is a hard disk partition
/media/richard/test is a USB flash drive
I received "illegal operation" error messages as symbolic links
were encountered.
"man cp" was too terse to be illuminating.
I think cp -a is your best bet. It will copy everything, shouldn't choke on links, and will also set permissions etc correctly on the target device, assuming you have permissions to do so (you should be doing the copy as root, always assuming you want to keep permissions and access modes intact).
I recently used it to copy hard disk partitions to a replacement SSD (some discussions about that are in the archives of this list) and it worked just dandy.
Mark