I'm off to gather more data, but I'm developing a deep suspicion that something with external usb disk support ain't right in fedora 12 x86_64.
With both the native usb on my motherboard and a pcie usb card, if I copy the fedora 13 alpha x86_64 DVD to the usb drive, the sha256sum checksum test fails on the copy.
If I do the same copy on the same hardware booted from my old fedora 10 x86_64 partition, the copy correctly matches the sha256sum test.
Anyone else with suspicious usb drive results on large files?
It will take a while, but I'm off to try this several times on both fedora 12 and fedora 10. If my results are consistent, I guess I'll submit a bugzilla (against the kernel?).