Re: [linux-lvm] summary of what I need to do to mount snapshot on XFS

["Heinz J . Mauelshagen" <mauelshagen@sistina.com>]

On Thu, Jan 10, 2002 at 09:38:08AM +1000, Adrian Head wrote:
> If this works for you - good.  I have had heaps of issues that I have been 
> working with various developers and trying to get fixed.
> 
> Basically if I used the SGI 2.4.17-xfs kernel with lvm-1.0.1rc4(ish) some 
> file systems would work but others would fail.  Some would fail on snapshot 
> creation, others would fail on snapshot mount and others would fail when the 
> snapshot overflowed.  When I upgraded LVM to lvm-1.0.1 other filesystems 
> issues were fixed but others broke again.  Check out the "Unable to get XFS, 
> ext3, reiserfs & LVM to coexist happily"
> http://marc.theaimsgroup.com/?l=linux-lvm&m=100994364215110&w=2
>  thread on linux-lvm / linux-xfs mail archives and see if any of this relates 
> to your problem.  With 2.4.17-xfs + lvm-1.0.1 upgrade patch + VFS-lock patch 
> ext2/3 & resierfs will operate correctly but XFS will fail at snapshot 
> creation.  You can do a little source code change and get a XFS snapshot 
> created and mounted; but then it will fail on an overfull snapshot.  These 
> problems are being worked on by myself and the great SGI XFS developers.
> 
> The lvm.c change you talk about I assume is the LVM_VFS_ENHANCEMENT change?  
> For some reason when adding the lvm-1.0.1 upgrade patch this disappears from 
> lvm.c   I have been able to get this to compile with the change but I have 
> forgoten what I did.  
> 
> This is one question I would like answered by the LVM gurus:  should #define 
> LVM_VFS_ENHANCEMENT still be there after upgrading to lvm-1.0.1?

Yes.

> What does 
> LVM_VFS_ENHANCEMENT actually do w.r.t lvm-1.0.1rc4(ish) and lvm-1.0.1?

What it did before: compile the VFS lock/unlock calls in.

> I 
> know that LVM_VFS_ENHANCEMENT in older LVM versions was the locking of the 
> VFS so that snapshots would be consistant - is this still correct and is it 
> still needed?

Yes.

> 
> For the "large discussion" you are talking about the "Unable to get XFS, 
> ext3, reiserfs & LVM to coexist happily" thread - hit me off list and I will 
> attempt to summarise it for you.
> 
> On Thu, 10 Jan 2002 06:09, Jeremy Hansen wrote:
> > My issue wasn't so much with how to create the snapshot but how to
> > simultaneously mount the snapshot with the live filesystem.  I saw a big
> > thread about having to uncomment from lvm.c, did that but then got
> > unresolved symbols...
> >
> > It seemed as if there were some issues and a large discussion related to
> > doing this with XFS.
> >
> > Thanks
> > -jeremy
> 
> -- 
> Adrian Head
> 
> (Public Key available on request.)
> 
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-- 

Regards,
Heinz    -- The LVM Guy --

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

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Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen@Sistina.com                           +49 2626 141200
                                                       FAX 924446
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