Re: mount failed after xfs_growfs beyond 16 TB

[Eric Sandeen <sandeen@xxxxxxxxxxx>]

Christian Guggenberger wrote:
> > xfs_db mojo.... ;)
> >
> > Note - no guarantee this will work - practise on an expendable
> > sparse loopback filessytem image by making a filesystem of slightly less
> > than 16TB then growing it to corrupt it the same way and then fixing it up
> > successfully.
> >
> > Once it's corrupted, unmount and run xfs_db in expert mode.
> > The superblock:
> >
> > blocksize = 4096
> > dblocks = 18446744070056148512
> > ...
> > agblocks = 84976608
> > agcount = 570
> >
> > An AG is ~43.5GB, so 570 AGs is 24.8TB. It's to big, and
> > we will only shrink by whole AGs. Hence we have to correct
> > agcount and dblocks.
>
> isn't the AG size 'agblocks * blocksize' == ~324 GB here ?
>
> got further input on a secondray superblock form the colleague:
> looks more reasonable, I'd say. Is there a way to manually recover sb0
> from sb1 ?

you can copy it over field-by-field.... not sure if there's an easier way.

-Eric