SCSI

Jack Harper harper at secureoutcomes.net
Tue Jan 23 11:40:28 CST 2018


Jim -

I appreciate the great SCSI information.

The hang is not at all frequent.

I do resets many times during a programming 
session as my "marvelous" code hangs or otherwise 
goes crazy and into thew weeds  :)    and I only 
see a SCSI hang every few days.

Regards,

Jack




At 10:28 AM 1/23/2018, jim stephens wrote:

>Scsi controllers are very sensitive to resets 
>and getting out of step with the state of the bus the initiators they control.
>
>Scsi can have multiple initiators, and you may 
>of course have a system which acts as a target, 
>but i'm guessing since you said drives, you have 
>a pretty common setup, a system with drives 
>attached, where the scsi device on your system is the initiator.
>
>One thing that throws off scsi is to do a reset 
>which comes from somewhere the initiator doesn't 
>know about.  many are not friendly when that 
>happens and just end up hung up.  Reset tells 
>all the devices to stand down, and it is 
>expected that an enumeration of the bus will 
>take place by all the initiator(s).
>
>That may have happened if you reset your other 
>processors or did something which affected the 
>initiator.  And the resets on most systems 
>usually hit all components, so I'd be surprised 
>if only the one processor was affected.
>
>thanks
>Jim

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Jack Harper, President
Secure Outcomes Inc
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Evergreen, Colorado 80439 USA

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