Re: Journaling: Surviving or allowing unclean shutdown?

[Daniel Phillips]

"Stephen C. Tweedie" wrote:
> 
> On Wed, Jan 03, 2001 at 05:27:25PM +0100, Daniel Phillips wrote:
> >
> > Tux2 is explicitly designed to legitimize pulling the plug as a valid
> > way of shutting down.  Metadata-only journalling filesystems are not
> > designed to be used this way, and even with full-data journalling you
> > should bear in mind that your on-disk filesystem image remains in an
> > invalid state until the journal recovery program has run successfully.
> 
> ext3 does the recovery automatically during mount(8), so user space
> will never see an unrecovered filesystem.  (There are filesystem flags
> set by the journal code to make sure that an unrecovered filesystem
> never gets mounted by a kernel which doesn't know how to do the
> appropriate recovery.)

Hi Stephen.

Yes, and so long as your journal is not on another partition/disk things
will eventually be set right.  The combination of a partially updated
filesystem and its journal is in some sense a complete, consistent
filesystem.

I'm curious - how does ext3 handle the possibility of a crash during
journal recovery?

--
Daniel