Running off USB, can't see SATA drive

[kilovar40]

So my GFH SATA drive died a while ago - the past weekend decided to revive the GFH and installed Arch to USB key using this link (thanks it works well).
https://archlinuxarm.org/platforms/armv5/seagate-goflex-home.

All is running well, but now I found a spare SATA drive and I want to use with the existing install. When I plug in the new SATA drive it boots from the USB as expected (because the SATA drive does not contain a boot image), but I cannot see the SATA drive anywhere with fdisk -l or in the /dev/ directory. The USB drive shows up as SDA.

It could be that the spare SATA drive I am trying to use is toast, but before I go out and buy a SATA to USB adapter to test it I thought I'd ask if there is a limitation in the kernel to see only one hard drive.

Should I be able to see the SATA drive if it is working correctly?

[WarheadsSE]

You should be able to see the drive.