Odd behavior of Wangtek 5525ES SCSI tape drive under 2.2.2 and A

[Daniel M. Eischen]

> I am the proud owner of a
>
> (ahc0:4:0): "WANGTEK 5525ES SCSI 73R1" type 1 removable SCSI 2
> st0(ahc0:4:0): Sequential-Access density code 0x0,  drive empty
>
> Wangtek 5525ES SCSI-2 tape drive (525MB QIC-525 drive).  It's connected to
> my brand-new Adaptec AHA-2940AU PCI SCSI controller (aic7860), on my
> FreeBSD 2.2.2-RELEASE system.
>
> This setup works pretty well.  I've already done several successful dumps
> to this device, and have created more tar tapes than I can shake a stick
> at.
>
> The weirdness comes with the `mt' command.  Basically, any "mt" command
> that causes the tape drive to spin (weof, retension, fsf, etc.) SOMETIMES
> (probably 1 in 10 times) causes the system to "soft hang".  Processes keep
> running, I can switch to another VC and login, or telnet to the machine
> over the network, etc.  BUT the mt process is hung -- I can't exit with
> Ctrl-C, or kill (even kill -KILL) it.  Ctrl-Z fails to suspend the thing,
> and the process fails to die on a reboot/shutdown (this results in the
> "syncing disks...giving up" message).  And the tape drive don't spin.
> 
> BUT, other commands that access the tape drive (tar, dump, even dd) work
> fine!!!

It sounds like the SCSI tape driver isn't giving the driver enough
time to retension, and attempting to (unsuccessfully) abort the command.
I notice the same thing when doing a tar using a HP C1533 DAT drive
when the tape is automatically retensioned.

This shouldn't lead to your having to push the big red button, though.
It sounds like a problem that will be fixed when Justins new SCSI CAM
gets incorporated ;-)

Can you find any ahc error messages in the logs?  I would expect the
logs to show Bus Device Resets and possibly SCSI Bus Resets when the
driver tries to abort the command.

Dan Eischen
deischen at iworks.InterWorks.org