> > attention to the RFC that Sean Doran pointed me at (rfc2001)-  although I was
> > talking to Bob Snively about this a couple of weeks ago and he and I are a
> > little dubious that pure congestion control is what's needed given the nature
> > of SCSI devices (he's of the opinion that as soon as a QFULL condition is
> > done, jam it to the max- hence my slight unease at anything in QFULL handling
> > that has race conditions or any amount of complexity other than requeing
> > logic).
> 
> I'm not sure this is rigth. It seems that some SCSI devices have a hard limit
> on the number of tag they can handle (for my quantun fireball it seems to be
> around 20), bumping it to the max (256) again would leave to another
> QFULL pretty soon, with a lot of xfer to requeue. We need an algorithm that
> can detect and stay around this limit.

But it mostly is true that a QFULL is always contingent upon things that can
change- so you can get a QFULL at 20 commands (if they're all 100MB xfer
lengths) or at 255 (if they're all trivial TUR's).

I think Bob has it right- keep jamming it.

-matt