Re: fsck more often when powerfail is detected (was Re: wishfulthinking about atomic, multi-sector or full MD stripe width, writes instorage)

From: tytso
Date: Sun Apr 04 2010 - 13:40:57 EST

On Sun, Apr 04, 2010 at 03:47:29PM +0200, Pavel Machek wrote:
> > Yes, but ext3 does not enable barriers by default (the patch has been
> > submitted but akpm has balked because he doesn't like the performance
> > degredation and doesn't believe that Chris Mason's "workload of doom"
> > is a common case). Note though that it is possible for dirty blocks
> > to remain in the track buffer for *minutes* without being written to
> > spinning rust platters without a barrier.
> So we do wrong thing by default. Another reason to do fsck more often
> when powerfails are present?

Or migrate to ext4, which does use barriers by defaults, as well as
journal-level checksumming. :-)

As far as changing the default to enable barriers for ext3, you'll
need to talk to akpm about that; he's the one who has been against it
in the past.

- Ted
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