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Gmane
From: Jeff Garzik <jeff <at> garzik.org>
Subject: Re: Linux 2.6.29
Newsgroups: gmane.linux.kernel
Date: Tuesday 24th March 2009 19:55:28 UTC (over 7 years ago)
Linus Torvalds wrote:
> But I really don't understand filesystem people who think that "fsck" is 
> the important part, regardless of whether the data is valid or not.
That's 
> just stupid and _obviously_ bogus.

I think I can understand that point of view, at least:

More customers complain about hours-long fsck times than they do about 
silent data corruption of non-fsync'd files.


> The point is, if you write your metadata earlier (say, every 5 sec) and 
> the real data later (say, every 30 sec), you're actually MORE LIKELY to 
> see corrupt files than if you try to write them together.
> 
> And if you write your data _first_, you're never going to see corruption 
> at all.

Amen.

And, personal filesystem pet peeve:  please encourage proper FLUSH CACHE 
use to give users the data guarantees they deserve.  Linux's sync(2) and 
fsync(2) (and fdatasync, etc.) should poke the block layer to guarantee 
a media write.

	Jeff


P.S.  Overall, I am thrilled that this ext3/ext4 transition and 
associated slashdotting has spurred debate over filesystem data 
guarantees.  This is the kind of discussion that has needed to happen 
for years, IMO.
 
CD: 3ms