Re: mount prob: "log inconsistent or not a log"

["Jonathan C. Detert" <Jonathan.Detert@msoe.edu>]

* Jonathan C. Detert <Jonathan.Detert@msoe.edu> [071219 20:44]:
> * David Chinner <dgc@sgi.com> [071219 19:59]:
> > On Wed, Dec 19, 2007 at 07:18:48PM -0600, Jonathan C. Detert wrote:
> > > * Timothy Shimmin <tes@sgi.com> [071219 18:53]:
> > > > Hi Jonathan,
> 
> -- snip --
> 
> > > > Jonathan.Detert@msoe.edu wrote:
> > > > >This is what /var/log/messages has to say about the mount attempt:
> > > > >-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> > > > >Dec 19 17:42:30 quartz kernel: [ 9701.960000] XFS mounting filesystem sdb
> > > > >Dec 19 17:42:30 quartz kernel: [ 9701.960000] XFS: Log inconsistent or not 
> > > > >a log (last==0, first!=1)
> > > 
> > > --snip --
> > > 
> > > > >-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> > > > >
> > > > Every 512 bytes of the log is stamped with the cycle#.
> > > > The cycle# is effectively the number of times the log has wrapped
> > > 
> > > -- snip --
> > > 
> > > > An "xfs_logprint -d /dev/sdb" will show what the cycle#s are
> > > > and where the log records are. It might give an idea of the
> > > > extent of the corruption.
> > > 
> > > Something occurred to me to point out:  the snapshot from yesterday has
> > > the same problem.  How can that be?  Is is possible that the log has
> > > been hosed for some time, and that the problem only reared its head now
> > > because I had to remount?  I.e. is it possible for an xfs fs to be
> > > mounted and used, even while the log is messed up?
> > 
> > No, it should not.

I just want to clarify - I mean to ask:

	Is it possible that an xfs filesystem which is in use by an o.s.,
	last mounted by the o.s. months ago, could have a corrupted log, and
	yet keep functioning until such time as a remount of it is attempted?

	I.e. if a log gets corrupted while the f.s. is in use, will anyone
	notice, until such time as an attempt to remount the f.s. is made?

I don't mean to ask:

	Is it possible to mount an xfs fs whose log is corrupted?

Thanks
-- 
Jon Detert
IT Systems Administrator, Milwaukee School of Engineering
1025 N. Broadway, Milwaukee, Wisconsin 53202, U.S.A.
--
Half a truth is often a great lie.