I have two external firewire drives which will no longer mount on any computer. When I run Disk Utility to verify them, it says:
Checking HFS Plus volume.
Invalid B-tree node size.
The volume needs to be repaired.
Volume check failed.
Error: The underlying task reported failure on exit (-9972)
The drives started malfunctioning after they had been mounted on a particular 400 MHz PowerPC G33 running 10.2.8.