Does TST == 001b break initiator software?

PJohansson PJohansson at
Fri Apr 3 13:57:06 PST 1998

* From the T10 (formerly SCSI) Reflector (t10 at, posted by:
* PJohansson <PJohansson at>
In a message dated 98-04-03 16:30:55 EST, ROWEBER at writes:

<<I DO NOT support making TST=000b obsolete. Therefore, I DO NOT support
making CLEAR TASK SET obsolete.>>

I'm left wondering if we're using the same language to communicate, Ralph.

I didn't suggest that TST equals zero be obsoleted. I didn't suggest that
CLEAR TASK SET be unconditionally obsoleted.

I am suggesting that when TST equals 001b we should obsolete CLEAR TASK SET.

The reasoning is that an initiator that issues CLEAR TASK SET to a TST equals
001b device is already broken because it won't get the behavior it expects.
Next step: when TST equals 001b CLEAR TASK SET collapses into ABORT TASK SET
(i.e., they have identical behaviors). Finally, if the initiator software
requires revision to operate correctly when TST equals 001b, why not disallow

This discussion would be improved a lot if we had some use models to examine.
What existing host software uses CLEAR TASK SET and what behavioral
assumptions are made about the target? Do these assumptions break when TST
equals 001b? I suspect they do, but then I'm not the guy writing an OS that


Peter Johansson
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