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Date:      Wed, 13 May 1998 17:56:27 +0200
From:      Stefan Grefen <grefen@carpe.net>
To:        fireston@lexmark.com
Cc:        gibbs@narnia.plutotech.com (Justin T. Gibbs), freebsd-scsi@FreeBSD.ORG
Subject:   Re: SCSI timeouts in dataout mode 
Message-ID:  <23007.895074987@hex.grefen.carpe.net>
In-Reply-To: Mik Firestone's message <199805131353.AA11660@interlock2.lexmark.com> of Wed, 13 May 98 09:53:45 EDT.
References:  <199805131353.AA11660@interlock2.lexmark.com> 

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In message <199805131353.AA11660@interlock2.lexmark.com>  Mik Firestone wrote:

[...]

> 
> I will make the observation that this error is somehow related to the amount
> of time it takes to write the file.  If it takes more then 10 seconds to
> write, we see this error.  We have not yet tried to read a large file to see
> what problems that can cause.
> 
> To hazard a guess, I really think this is some strange interaction between th
> e
> scsi code and the cache on the HP.  Either the HP is doing the right kind of
> handshaking or the FreeBSD box is missing it.  But this is only a guess.

If I remember correctly some of those RAID arrays report good-status even if
the data is not on disk yet (either assuing or providing UPS for the array).

If the Cache is full you have to wait until some space is freeed, so 
the command 'hangs' and times out. 
The SCSI analyser would just see an initial transfer and no reconnection.

Try increasing the timeout by a factor of  2 or 4 (or 8) and see if it still 
happens.  Or you could try configure the RAID for write-through instead of
write-back. But than you should turn on tags ... 
(I think you can configure some HP-arrays with a terminal over a serial 
line)

> 
> -- 
> Mik Firestone fireston@lexmark.com
> If ever I become an Evil Overlord:
> All naive, busty tavern wenches in my realm will be replaced with surly,
> world-weary waitresses who will provide no unexpected reinforcement and/or
> romantic subplot for the hero or his sidekick.
> 
> To Unsubscribe: send mail to majordomo@FreeBSD.org
> with "unsubscribe freebsd-scsi" in the body of the message

--
Stefan Grefen                           Am Hummertal 4, 55283 Nierstein, Germany
grefen@carpe.net                        +49 6133 927484   Fax:+49 6133 927486
Idiot, n.:
        A member of a large and powerful tribe whose influence in human
affairs has always been dominant and controlling.
                -- Ambrose Bierce, "The Devil's Dictionary"

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