SCSI-2 Parity Errors
lchen at pyramid.com
Wed Mar 15 11:39:30 PST 1995
On Mar 15, 10:32am, Denis Brockus wrote:
> Subject: SCSI-2 Parity Errors
> I am having a hard time determining what to do from a target point of view
> when I detect a parity error. I know that a target should not reply to a
> selection if there is a parity error in the SELECTION phase.
> When the target is in MESSAGE OUT phase, there are two options after
> retries have been exhausted:
> 1) return CHECK CONDITION status and set the sense key to ABORTED
> COMMAND and the additional sense code to MESSAGE ERROR.
> 2) indicate an exception condition by performing an unexpected
> disconnect. (? what happens to the I/O process? is it aborted?)
> What should happen if parity errors are detected in COMMAND and/or DATA OUT
> phase? How should retries be performed in each of these situations and
> what should happen after retries have been exhausted?
> Thanks, Denis
As a suggestion, Zadian's Host Basher software is quite helpful in
learning the details of error recovery.
In general, a target device has three options as you mentioned when a
parity error is detected:
2) check condition
for data phases, the target must remember to reset the host's current
data pointer before data phases are retried.
> _/_/_/_/ _/_/_/_/ | Denis Brockus
> _/ _/ _/ _/ | denis at arraytech.com
> _/ _/ _/ _/ |
> _/ _/ _/_/_/_/ | Array Technology
> _/ _/ _/ _/ | 4775 Walnut Street, Suite B
> _/ _/ _/ _/ | Boulder, Colorado 80301
> _/_/_/_/ _/_/_/_/ | Tel(303)938-6057 Fax(303)444-0059
>-- End of excerpt from Denis Brockus
-m------- Lawrence Chen Pyramid Technology Corporation
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-- End of excerpt from Lawrence Chen
-- And something to think about ...
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