AIC7902 w/ seagate U320 drive issue on releng-4 (and current)

[Don Bowman]

> From: Justin T. Gibbs [mailto:gibbs at scsiguy.com]
> 
> > FYI, i've solved this problem for me by moving to 
> > firmware version 5 on the ST318453LW (U320 15KRPM 18GB)
> > seagate drive.
> 
> This is exactly what I was going to suggest.  0004 is known
> bad in packetized operation.  Your test to drop the speed to
> 160MB/s was a good thought, but for the 790X controllers, we
> will still attempt to run with packetized protocol, assuming
> the device supports it, even when you reduce the negotiated
> rate.  You can disable packetized protocol in SCSI-Select which
> would probably have allowed you to limp along until you got
> updated firmware.
> 
> Sadly, 0005 is not perfect.  I have seen situations where under
> hight tag load 0005 still drops trasactions.  I believe that
> Seagate has a fix for this, but it has yet to be put into
> release level firmware.  You might want to touch base with
> them in another month to see if they have released a follow
> on to 0005.

I wonder if the driver could back-off or do some test first.
I thought i was good when i upgraded all these systems from 3 to 4,
and am now faced with the unpleasant prospect of upgrading many
systems that are @ remote customer sites.

interestingly, 004 was fine until a recent driver rev (or at
least, the problem did not manifest).

Why would the behaviour be such that the drive disappears from
the SCSI chain and not even a system reset fixes it? I'm very
surprised that resetting the motherboard doesn't reset the drive,
only a powercycle does in this case.

Why would the 160 version of the same drive not have the same
bug? I guess that's a question for seagate :)

So after updating 15 test systems and running 'dd' for some hours,
1 of them showed the same card-state dump 1 time.

Should i just drop the number of tags down to 32 or 64 on spec,
or is there another cause likely?


--don