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Date:      Tue, 13 Apr 1999 19:22:33 -0600 (MDT)
From:      "Kenneth D. Merry" <ken@plutotech.com>
To:        asami@FreeBSD.ORG (Satoshi - Ports Wraith - Asami)
Cc:        scsi@FreeBSD.ORG
Subject:   Re: timed out while idle?
Message-ID:  <199904140122.TAA06901@panzer.plutotech.com>
In-Reply-To: <199904140059.RAA49792@silvia.hip.berkeley.edu> from Satoshi - Ports Wraith - Asami at "Apr 13, 1999  5:59:32 pm"

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Satoshi - Ports Wraith - Asami wrote...
>  * From: "Kenneth D. Merry" <ken@plutotech.com>
> 
>  * > Wow, 60 seconds?  That's indeed a pretty good lunch. :)
>  * 
>  * Yep.
> 
> Do you think it's a bad idea to reduce it to something like 15
> seconds?  Not that it matters much but the disk reads pretty much
> stall during that time, and if it's not going to catch any false
> positives, I'd like them to recover faster.  Is there some way to find
> out if there's something that came back after 15 seconds but before
> 60?

The reason the timeout is as high is it is now is because of some devices
(zip drives?) that spin down their media and then spin back up when they
get a command.

It takes them a little bit to spin up, so that's why the timeout is as long
as it is.

As far as figuring out whether something came back between 15 and 60
seconds, probably the only way to do that would be to timestamp each CCB as
it is sent down to the controller.  It can be done, but is it really worth
it?

>  * I don't think the timeouts in and of themselves will cause panics, unless
>  * maybe the drive never recovers.  
> 
> How do I find out if the drive recovered?

If it is still responding.  In most cases that I've seen a BDR will cause
the drive to wake up and start functioning again.

>  * I dunno what's going on there.  It could be indirectly caused by the
>  * timeout, but I really don't know how that could happen.
> 
> Next time I'll try to catch it with a debug kernel.

That'll be more helpful.  At least you'll be able to (hopefully) see exactly
which line caused the panic.

Ken
-- 
Kenneth Merry
ken@plutotech.com


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