The drive indeed comes up as frozen, but this is cleared by hot power cycling the drive.
Ahh.. have you verified that, by re-running
hdparm -I after the unplug/replug? If it is not actually cleared, then I know what's going on. The ACPI BIOS is re-freezing the drive after hotplug. Bad.
But actually, it's not the BIOS, but rather the ACPI interpreter in the kernel. Which can be disabled!
The kernel parameter (kernel boot line in GRUB) for this is:
libata_noacpi=1If you can figure out how to enter that parameter at the boot prompt from your LiveCD, then it will probably let things work as they should.
An even more drastic way to do this would be to also disable ACPI
globally at boot:
libata_noacpi=1 acpi=off-ml