U3 kernel breaks tape library access with "mtx" via /dev/sg*

[Dax Kelson <dax gurulabs com>]

The "mtx" command is AFAIK the only open source command available in
Linux for managing tape libraries, ie, being to control the robotic arm
to load a tape from a specific slot into a tape drive.

The "mtx" command has long shipped with Red Hat up to and including
FC3t1.

For whatever reason (oversight during overzealous package removal?) it
was not included in RHEL3.

On my fully paid-up subscribed RHEL3 box, I fixed this by recompiling
the mtx SRPM from Fedora.

This has worked great until I upgraded to the U3 kernel (2.4.21-20.EL).
Now I can no longer use the mtx command.

# mtx -f /dev/sg3 status
cannot open SCSI device '/dev/sg3' - No such device or address

Comments?

Dax