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Date:      Thu, 5 Apr 2007 10:00:05 +0200 (CEST)
From:      Oliver Fromme <olli@lurza.secnetix.de>
To:        freebsd-stable@FreeBSD.ORG, chris#@1command.com
Subject:   Re: NFS == lock && reboot
Message-ID:  <200704050800.l35805AQ086224@lurza.secnetix.de>
In-Reply-To: <20070404073939.h9p3mgp2m88kswk8@webmail.1command.com>

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Chris H. <chris#@1command.com> wrote:
 > Oliver Fromme wrote:
 > > [...]
 > > However, I don't think that your actual problem (lock-up
 > > and panics) is related to rpc.lockd or rpc.statd.  It
 > > rather sounds like something else is wrong with your
 > > machine.  NFS works perfectly fine for me, including
 > > copying huge files.
 > > 
 > > You wrote that you had a lot of crashes that accumulated
 > > many files in lost+found.  Well, maybe your filesystem
 > > was somehow damaged in the process.  It is possible to
 > > damage file systems in a way that can lead to panics, and
 > > it's not necessarily detected and repaired by fsck.
 > 
 > Indeed. I /too/ considered this. However, I largely dismissed this
 > as a possibility as most all of them are 0 length in size. The others
 > are fragments of logs. I'm not /completely/ ruling this out though.

The files in lost+found aren't the problem.  The problem
is the things that you cannot see, and fsck won't move
those to lost+found.

In particular, if you use softupdates on drives that have
write-caching enabled, or on drives that illegally cache
data even if it's disabled (be it intentionally or because
of bugs in the firmware), it's almost guaranteed that the
FS will take damage beyond repair on a crash, and even more
so after several crashes.

Another potential cause of problems is the background fsck
feature in FreeBSD 6.  I'm not sure if it has been fixed
in 6-stable, maybe it has.  I don't want to spread FUD.
But in the past, if a machine crashed and rebooted during
a background fsck, that was almost a guarantee for damage
beyond repair, too.  That's why I always disable background
fsck on my machines.  (Let me repeat:  It _might_ be fixed
in 6-stable, I don't know.  I haven't seen a definitive
confirmation of it being fixed on the mailing lists so
far.  If somebody knows otherwise, please correct me.)

Best regards
   Oliver

-- 
Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M.
Handelsregister: Registergericht Muenchen, HRA 74606,  Geschäftsfuehrung:
secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün-
chen, HRB 125758,  Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart

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

"Python is an experiment in how much freedom programmers need.
Too much freedom and nobody can read another's code; too little
and expressiveness is endangered."
        -- Guido van Rossum



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