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Date:      Mon, 29 Aug 2005 18:48:00 -0400
From:      Chuck Swiger <cswiger@mac.com>
To:        Matthias Buelow <mkb@incubus.de>
Cc:        freebsd-stable@freebsd.org
Subject:   Re: Sysinstall automatic filesystem size generation.
Message-ID:  <431390A0.5080007@mac.com>
In-Reply-To: <20050829215613.GD1462@drjekyll.mkbuelow.net>
References:  <20050829120415.GA1462@drjekyll.mkbuelow.net> <200508291836.j7TIaVEk013147@gw.catspoiler.org> <20050829185933.GB1462@drjekyll.mkbuelow.net> <431362ED.9030800@mac.com> <20050829204714.GC1462@drjekyll.mkbuelow.net> <43137AFB.9060304@mac.com> <20050829215613.GD1462@drjekyll.mkbuelow.net>

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Matthias Buelow wrote:
> Chuck Swiger wrote:
>> Yet you seem willing to spend time discussing the matter...?
> 
> Because it's somewhat of my pet peeve and I always see the mantra-like
> repetition of the argument that "you have to disable the write-back
> cache if you want any safety at all",

No, there are other possible solutions which have been mentioned.

I reiterate my question: have you tried adjusting the syncer sysctl's and 
seeing whether FreeBSD is more stable in the event of a power failure?

[ ... ]
>>>One often sees the "softupdates" argument being fielded by FreeBSD
>>>advocates, typically against Linux users with journalled fs, on web
>>>forums, usenet and other less authoritative (and knowledgable)
>>>places of discussion, and it is often presented as if it were some
>>>kind of magic bullet that makes filesystem corruption impossible.
>>
>>"Often?"  Strawman test: can you point out 3 examples by message-id or URL?
> 
> A Google search finds them quickly:
> 
> http://www.heise.de/ix/foren/go.shtml?read=1&msg_id=7335045&forum_id=70615
> (german, argument is that "softupdates is at least a match for a
> journalled fs"),
> 
> http://lists.freebsd.org/pipermail/freebsd-questions/2003-June/009967.html
> ("FS + SoftUpdates is much better than journaling!")
> 
> http://aussatz.antville.org/topics/HowTos/
> (german, argument is "1. practically nothing can break when power
> goes out", and even that you can switch off the machine without any
> problems, except for losing the files that have been written to in
> the last seconds.  Of course no mentioning of disk cache or any
> sophistication whatever.)

Conclusion: if you're looking for unbridled FreeBSD advocacy on these lists or 
in the FreeBSD documentation, you've found very little.  A one-line post from 
2003: gosh, someone expressed a strong opinion, and even that was promptly 
followed up with:

> FFS+SU does have the disadvantages that a full fsck is still needed
> (run in the background), and you risk losing the last `sysctl
> kern.metadelay` seconds worth of files written just before a crash.

...by Dan Nelson.

I'm going to skip the rest of the monologue and the Dubai Nad al-Sheba golf 
club as well, but thanks anyway.

-- 
-Chuck




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