Date: Mon, 26 Aug 2002 21:02:03 -0700 (PDT) From: "Fedor G. Pikus" <pikus@pikus.net> To: "Justin T. Gibbs" <gibbs@scsiguy.com> Cc: <aic7xxx@FreeBSD.ORG> Subject: Re: Strange log messages from AHA2940UW Message-ID: <Pine.LNX.4.33.0208262100440.13328-100000@valinor.pikus.net> In-Reply-To: <Pine.LNX.4.33.0208261916180.13328-100000@valinor.pikus.net>
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Spoke too soon... I saw another SDTR message triplet in the log,
with DVD-RAM and CD both with media, and long after DVD-RAM
recognized the disk. But it's apparently rare now.
On Mon, 26 Aug 2002, Fedor G. Pikus wrote:
> I tried out your sugestion, the results are ... interesting.
> First of all, if I have a CD in the CD drive, and a DVD-RAM in the
> DVD-RAM, I don't get the SDTR message. How does the CD enter the
> picture I have no idea, it's an ATAPI CD on ide-scsi.
>
> I also noticed that it takes awhile for the DVD-RAM to chew on the
> disk after I stick one in, and if I start an operation before that
> (like, try to mount or mke2fs it) it will succeed eventually, but
> with lots of SDTR messages.
>
> Now, the bad news: with no SDTR messages copying 2G of data from
> hard drive to DVD-RAM still drives the load up to 5 and even more,
> X freezes every few seconds, while top and xosview show no CPU activity,
> and no processes consume any significant resources.
>
> The freezing is not related to reading fron disk: I can copy disk to disk
> with no problem (CPU will be loaded if I do, but the system remains
> responsive). Also, I can freeze the system by copying few files to DVD-RAM
> so nothing actually gets written yet (everything stays in buffers, with 1G
> of RAM kernel allocates lots and lots of them). Then I type "sync",
> DVD-RAM light comes on, and everything else starts freezing up and
> stuttering until it's done syncing.
>
> There are no messages in the log when it happens. I could enable some more
> verbosity if I new what to look for...
>
>
> On Mon, 26 Aug 2002, Justin T. Gibbs wrote:
>
> > > First, the problem, in a nutshell:
> > > I'm getting alot of the following in my log:
> > > kernel: (scsi0:A:3:0): Sending SDTR period 19, offset f
> > > kernel: (scsi0:A:3:0): Received SDTR period 19, offset f
> > > kernel: ^IFiltered to period 19, offset f
> > >
> > > Usually when I start getting these, my SCSI devices become slow, and
> > > quite often the whole system starts freezing for a second or two
> > > (total freeze, mouse is frozen in X) then wakes up, then freezes again.
> > > System load goes way up, to 4 or 5, but top does not show anything
> > > actually using the CPU.
> > > The freezing happens less often if I give Adaptec its own IRQ.
> > > What does the message mean, what's wrong, and how do I fix it?
> >
> > My guess is that you have a daemon probing your CDROM drives to see
> > if they have any media. This is usually done via a "Test Unit Ready"
> > command. If the device does not have any media in its drive, it
> > will respond to the TUR with check condition status. The aic7xxx
> > driver will always renegotiate with a device when a check condition
> > occurs since it may indicate that the device lost power and thus
> > the negotiated transfer agreement. I don't know why this would cause
> > your system to slow down noticibly. You don't want to be negotiating
> > all of the time since it does hog some SCSI bus cycles, but it is not
> > computationally intensive.
> >
> > To test my theory, stick media in your drives the next time you see
> > the messages on your console. They should go away.
> >
> > --
> > Justin
> >
>
>
--
Fedor G. Pikus
WWW: http://www.pikus.net/~pikus/
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