Stefan Esser wrote:
>There is one new explanation for your problems,
>which was found by somebody doing extensive tests
>under FreeBSD. Seems that the generic SCSI code 
>may cause problems with certain drives !

>A few drives seem to strongly dislike
>this command [start unit], after they once received a command
>with a tag!


>It is well possible, that it fully supports tags. 
>It is just picky about non-tagged commands (even
>NOP commands) sent when any tagged command is 
>active.

And it has every right to do so:

SCSI-2 7.8: " An initiator may not mix the use of tagged and untagged
queuing for I/O processes to a logical unit, except during a
contingent allegiance or extended contingend allegiance condition ..."

7.8.2:  "An I/O process received without a queue tag message, while
there are any tagged I/O commands in the command queue from the same
initiator, is an incorrect initiator connection (see 7.5.2), unless
there is a contingent allegiance or extended contingent allegiance
condition."

The same holds when a target receives a tagged command while a
untagged command from the same initiator is in its command queue.

I figure the problem isn't with the generic SCSI code but with your
driver violating the standard.

-- 
Christoph Badura	bad@flatlin.ka.sub.org

You don't need to quote my .signature.  Everyone has seen it by now.
Besides, it doesn't add anything to the current thread.