Re: Linux 2.6.29

Bill Davidsen
2009-03-30T19:03:22Z

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