Yep, my answer when cp or scp is not working well is always to break out rsync, even if I'm just copying files over to an empty location.
I've had good luck with the -H option, though it is slower than without the option. I have never copied a filesystem with nearly as many files as the OP with -H; the most I've done is probably a couple million, consisting of 20 or so hardlinked snapshots with probably 100,000 or 200,000 files each. rsync -H works fine for that kind of workload.
I've had good luck with the -H option, though it is slower than without the option. I have never copied a filesystem with nearly as many files as the OP with -H; the most I've done is probably a couple million, consisting of 20 or so hardlinked snapshots with probably 100,000 or 200,000 files each. rsync -H works fine for that kind of workload.