Re: Fix(es) for ext2 fsync bug

[Dawson Engler]

> On Tue, Feb 20, 2007 at 01:30:25PM -0800, Junfeng Yang wrote:
> > On 2/20/07, Valerie Henson <[EMAIL PROTECTED]> wrote:
> > >
> > >Google. (GoogleFS runs on top of ext2.)
> >
> > It's surprising to know that... I guess they reply on GoogleFS's own
> > replication and checksumming for consistency.
> 
> Yep, they just want a local file system with ultrafast on-line
> performance.  They don't care about recovery time particularly because
> of the GoogleFS replication (although I heard rumors they have some
> fast fsck scheme, maybe resembling the dirty bit stuff I did last
> year).

Actually, according to the GFS paper (which may be out of date), for
the chunkservers that is true, but for their "master" they really want
fast recovery as a way to reduce mean-time-to-repair (and thus increase
availability).

Though, given that they have shadow masters perhaps everyone is happy as
long as master recovery usually fast.

Dawson
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Re: Fix(es) for ext2 fsync bug

[Dawson Engler]

> It was my understanding from the persentation of Dawson that ext3 and jfs  
> have
> same problem. It is not an ext2 only problem. Also whatever solution we  
> adopt
> we need to be sure that we test it using the eXplode methodology.

apologies for dropping in randomly into the discussion: if this is
about the crash-during-recovery bugs, the specific ones i discussed
have been fixed in jfs and ext3 (junfeng: this is correct, right?).

i should have made this clear in the talk (along with many other things:
grabbing junfeng's slides and blathering about them w/o preperation is
not the right algorithm for giving a good talk.)

the other error --- fsync of file data on ext2 that reuses a freed inode
from a file that was not flushed to disk  is still open.
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