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Date:      Mon, 01 Jun 1998 20:51:51 -0400 (EDT)
From:      Simon Shapiro <shimon@simon-shapiro.org>
To:        Mike Smith <mike@smith.net.au>
Cc:        Karl Pielorz <kpielorz@tdx.co.uk>, tcobb <tcobb@staff.circle.net>, "freebsd-current@freebsd.org" <freebsd-current@FreeBSD.ORG>, Michael Hancock <michaelh@cet.co.jp>
Subject:   Re: DPT driver fails and panics with Degraded Array
Message-ID:  <XFMail.980601205151.shimon@simon-shapiro.org>
In-Reply-To: <199805292208.PAA01191@dingo.cdrom.com>

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On 29-May-98 Mike Smith wrote:
>> 
>> I am routinely running a Dual DPT with 38 drives on 6 busses.  On
>> 3.0-CURRENT SMP.  The system did lose disk drives, either intentionally,
>> or
>> by accident.  I cannot confirm any of Mr. Cobb's finding.  I have not
>> been
>> funished with any data, including the panic point, which I suspect is
>> not
>> in the DPT code.  I am still waiting for such data.
> 
> I'd just like to point out that the "biodone: buffer not busy" panic 
> doesn't come from the DPT driver, but may be caused by it calling 
> biodone() on a buffer that the system does not believe is busy.
> 
> These situations are worth analysing, and I hope to see you and Troy
> resolving this one, even if it means that you point the finger
> elsewhere.

I got these particularly with tape devices.  Especially if there are two
tape drives on the system and yoy try to (for example) cpio to both
independently.  I put a ton of debugging code in the DPT driver to try and
catch the DPT sending biodone twice on the same request and am pretty
comfortable the driver is not it.  Especially when the st.c peripheral
driver will do it almost consistently, and the disks will almost never do
that.  Since the DPT driver does not know a disk from a cucamber, I doubt
it is at fault.  But any persistent test cases are very welcome.

Simon


---


Sincerely Yours, 

Simon Shapiro                                           Shimon@Simon-Shapiro.ORG
                                                        770.265.7340

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