Re: Linux 2.6.29

Jeff Garzik
2009-03-24T19:57:39Z

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.