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Date:      Wed, 29 May 2013 15:05:13 +0200 (CEST)
From:      Oliver Fromme <olli@lurza.secnetix.de>
To:        freebsd-stable@FreeBSD.ORG
Subject:   Re: 9.1-stable: ATI IXP600 AHCI: CAM timeout
Message-ID:  <201305291305.r4TD5DAP037954@grabthar.secnetix.de>
In-Reply-To: <201305290809.r4T89EvT024069@grabthar.secnetix.de>

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Now I have some more information ...

The problem disappears when I disable NCQ, i.e. set the
number of tags to 1 with camcontrol.  Using binary search
I found out that the problem also disappears with 2 tags,
but with 3 tags I get the same amout of errors as with
the default of 32 tags.

Interestingly, the problems also disappears when I reduce
the SATA level from II to I (i.e. from 3 to 1.5 Gbit/s),
even if the NCQ tags are left at the default of 32.

Now the question is:  Is it better to reduce the NCQ tags
from 32 to 2, or to reduce the SATA bandwidth from 3 Gbps
to 1.5 Gbps?  What is more likely to impact performance
on a mixed server with shell users, apache, sendmail, DNS
and a few other things?

Best regards
   Oliver


-- 
Oliver Fromme,  secnetix GmbH & Co. KG,  Marktplatz 29, 85567 Grafing
Handelsregister:  Amtsgericht Muenchen, HRA 74606, Geschäftsfuehrung:
secnetix Verwaltungsgesellsch. mbH, Handelsreg.: Amtsgericht München,
HRB 125758, Geschäftsführer:  Maik Bachmann,  Olaf Erb,  Ralf Gebhart

FreeBSD-Dienstleistungen/-Produkte + mehr: http://www.secnetix.de/bsd

In my experience the term "transparent proxy" is an oxymoron (like jumbo
shrimp).  "Transparent" proxies seem to vary from the distortions of a
funhouse mirror to barely translucent.  I really, really dislike them
when trying to figure out the corrective lenses needed with each of them.
        -- R. Kevin Oberman, Network Engineer



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