To: linux-kernel@vger.kernel.org
From: Bill Davidsen <davidsen@tmr.com>
Subject: Re: Linux 2.6.29
Date: Mon, 30 Mar 2009 15:02:44 -0400
Message-ID: <gqr50k$4aq$1@ger.gmane.org>
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Andreas T.Auer wrote:
> On 30.03.2009 02:39 Theodore Tso wrote:
>> All I can do is apologize to all other filesystem developers profusely
>> for ext3's data=ordered semantics; at this point, I very much regret
>> that we made data=ordered the default for ext3.  But the application
>> writers vastly outnumber us, and realistically we're not going to be
>> able to easily roll back eight years of application writers being
>> trained that fsync() is not necessary, and actually is detrimental for
>> ext3.

> And still I don't know any reason, why it makes sense to write the
> metadata to non-existing data immediately instead of delaying that, too.
> 
Here I have the same question, I don't expect or demand that anything be done in 
a particular order unless I force it so, and I expect there to be some corner 
case where the data is written and the metadata doesn't reflect that in the 
event of a failure, but I can't see that it ever a good idea to have the 
metadata reflect the future and describe what things will look like if 
everything goes as planned. I have had enough of that BS from financial planners 
and politicians, metadata shouldn't try to predict the future just to save a ms 
here or there. It's also necessary to have the metadata match reality after 
fsync(), of course, or even the well behaved applications mentioned in this 
thread haven't a hope of staying consistent.

Feel free to clarify why clairvoyant metadata is ever a good thing...

-- 
Bill Davidsen <davidsen@tmr.com>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot

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