I just built up a Buffalo TeraStation NAS, Model TS-TGL, with two 2TB Hitachi DeskStar (7200rpm, 32MB cache) hard drives configured as a RAID1 array. The Ethernet port on the Buffalo is rated as a 1000Mbps port.
I did a test run, transferring approximately 550GB of music files from a USB 2.0 drive on a Dell GX260 desktop through the Dell's 1000Mbps network port via a wired network with a single 1000Mbps switch also rated at 1000Mbps and then directly into the TeraStation's port.
I used the latest version of Beyond Compare (Scooter Software) to sync the NAS with the USB.
It took 25 hours to complete the file transfer! This is an average transfer rate of 48.9 Mbps, far short of what USB 2.0 and a 1000Mbps network and either hard drive setup should be capable of delivering.
How long does it take to transfer a 1GB file from the desktop to the NAS? How fast is the USB 2.0 drive connected to the Dell GX260? That probably is where the bottleneck is. Besides, you can't expect high transfer rates when copying a bunch of small files.
The USB 2.0 drive successfully copied the 512.6GB set of files to another USB 2.0 drive on the same machine in about 8 hours, so I don't think it's the USB drive itself that is the limiting factor.
It's true that there are a lot of files, but they aren't all that small. They're typically about 25MB each, but of course they're in hundreds if not several thousands of different folders on the USB drive, and there certainly are thousands of files, each representing 1 track from a CD. I hadn't thought of that as a contributor to the problem, but maybe it is.
I'll try the desktop to NAS test next, but what I think I'll do is copy something like 10GB worth of the subset of folders and files.
I'm not sure where I'd find a single 10GB file. Suggestions?