Re: xfs_check problems on 3.6TB fs

[Frank Hellmann <frank@xxxxxxxxxxxxx>]

Hi Steve!

I think if anybody can spend some time to "extend" (fix) the way 
xfs_db/xfs_check and xfs_repair are handling large filesystems under 
linux, this would be really appreciated. I think 2TB+ filesystems on 2GB 
system memory will get so common over the next couple of months that 
this really needs to be adressed. Just my opinion...

I had a look into the xfs_db sources today and I still have no clue what 
is going on. There has been so much effort put in there (means a lot of 
code to understand), so maybe somebody with more expirience with the xfs 
tools can take a look?

        Thanks. Cheers,

                        Frank...

Steve Lord wrote:
> Michal Szymanski wrote:
>
> > Hi Frank,
> >
> > Thanks for your comments.
> >
> >
> > > > The oss.sgi.com/projects/xfs pages content suggests that actually 
> > > > 'fcsk'
> > > > is not needed anymore on a journalling FS like XFS. So maybe we can 
> > > > just
> > > > live without it?
> >
> >
> >
> > > No. There will be times, you'll need it. Powerloss is never going to 
> > > give you predictable results.
> >
> >
> >
> > > That would support my theory that there is a wrap-around bug 
> > > somewhere in xfs_check. It is not in xfs_repair. so I'll give it a 
> > > try and have a look.
> >
> >
> >
> > Still, if I am correct, 'xfs_check' gives just information on the FS
> > status and it is 'xfs_repair' that does the real job. So the 'xfs_check'
> > seems not to be that important.
> >
> > Michal Szymanski
>
> xfs_check is a wrapper around xfs_db, it does a fairly extensive
> metadata consistancy check, but does not fix anything up. xfs_repair
> is the tool for fixing things.
>
> I remember cases on Irix were we had to build a special 64 bit
> version of the tool (to get a larger address space), and get
> the customer to add more swap to succeed in running to completion.
>
> These programs have been put on a diet, but the memory demands of
> repairing/checking really large filesystems are still significant.
>
> Steve

--
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Frank Hellmann          Optical Art GmbH           Waterloohain 7a
DI Supervisor           http://www.opticalart.de   22769 Hamburg
frank@xxxxxxxxxxxxx     Tel: ++49 40 5111051       Fax: ++49 40 43169199