LVM Snapshots

LVM Snapshots

[Christoph Pleger]

Hello,

I am using a 2.4.22 kernel from www.kernel.org together with an XFS
patch from SGI. I want to use LVM for creating snapshots for backups,
but I found out that I cannot mount the snapshots of journalling
filesystems (EXT3, XFS, Reiser). Only JFS snapshots can be mounted.

My research on internet gave the result that a kernel-patch must be used
to solve that problem, but I could not find such a patch for Linux
2.4.22, so where can I get it?

Kind Regards
  Christoph 

PS: I do not know if it is of interest, but my distribution is Debian
woody with LVM 1.0.

Re: LVM Snapshots

[Marc-Christian Petersen]

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On Wednesday 15 October 2003 17:40, Christoph Pleger wrote:

Hi Christoph,

> I am using a 2.4.22 kernel from www.kernel.org together with an XFS
> patch from SGI. I want to use LVM for creating snapshots for backups,
> but I found out that I cannot mount the snapshots of journalling
> filesystems (EXT3, XFS, Reiser). Only JFS snapshots can be mounted.
> My research on internet gave the result that a kernel-patch must be used
> to solve that problem, but I could not find such a patch for Linux
> 2.4.22, so where can I get it?

Marcelo decided not to apply that needed patch. Here it is for you to play 
with :) ... It'll apply with offsets to 2.4.23-pre7.

ciao, Marc

[-- Attachment #2: LVM-v1.0.7-2.4-22-pre9-VFS-lock.patch.bz2 --]
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Re: LVM Snapshots

[Philippe Troin]

Marc-Christian Petersen <m.c.p@wolk-project.de> writes:

> On Wednesday 15 October 2003 17:40, Christoph Pleger wrote:
> 
> Hi Christoph,
> 
> > I am using a 2.4.22 kernel from www.kernel.org together with an XFS
> > patch from SGI. I want to use LVM for creating snapshots for backups,
> > but I found out that I cannot mount the snapshots of journalling
> > filesystems (EXT3, XFS, Reiser). Only JFS snapshots can be mounted.
> > My research on internet gave the result that a kernel-patch must be used
> > to solve that problem, but I could not find such a patch for Linux
> > 2.4.22, so where can I get it?
> 
> Marcelo decided not to apply that needed patch. Here it is for you to play 
> with :) ... It'll apply with offsets to 2.4.23-pre7.

What was the reason? I cannot find this thread in the archives...

Phil.

Re: LVM Snapshots

[Marc-Christian Petersen]

On Wednesday 15 October 2003 18:53, Philippe Troin wrote:

Hi Philippe,

> Marc-Christian Petersen <m.c.p@wolk-project.de> writes:
> > On Wednesday 15 October 2003 17:40, Christoph Pleger wrote:
> >
> > Hi Christoph,
> >
> > > I am using a 2.4.22 kernel from www.kernel.org together with an XFS
> > > patch from SGI. I want to use LVM for creating snapshots for backups,
> > > but I found out that I cannot mount the snapshots of journalling
> > > filesystems (EXT3, XFS, Reiser). Only JFS snapshots can be mounted.
> > > My research on internet gave the result that a kernel-patch must be
> > > used to solve that problem, but I could not find such a patch for Linux
> > > 2.4.22, so where can I get it?
> >
> > Marcelo decided not to apply that needed patch. Here it is for you to
> > play with :) ... It'll apply with offsets to 2.4.23-pre7.
>
> What was the reason? I cannot find this thread in the archives...

it was a private mail. Pasting relevant stuff:

---------------------------------------------------------------------

Re: Patches
Date: 01.09.2003 03:42
From: Marcelo Tosatti <marcelo@parcelfarce.linux.theplanet.co.uk>
To: Marc-Christian Petersen <m.c.p@wolk-project.de>
CC: Marcelo Tosatti <marcelo@conectiva.com.br>, Alan Cox 
<alan@lxorguk.ukuu.org.uk>

On Sun, 31 Aug 2003, Marc-Christian Petersen wrote:

> Hi Marcelo,
> 
> I just want to know what's wrong with these patches I've sent to you:
> 
> 
> - [PATCH 2.4.23-pre1] lowlatency fixes -12
Want to add Andreas VM stuff first.

> 
> - [PATCH 2.4.23-pre1] LVM 1.0.7 ADDON: Allow snapshots on journaling
>                                        filesystems

LVM has already been updated on 2.4.23-pre. Lets do more changes later on.

---------------------------------------------------------------------


ciao , Marc

Re: LVM Snapshots

[Philippe Troin]

Marc-Christian Petersen <m.c.p@wolk-project.de> writes:

> On Wednesday 15 October 2003 18:53, Philippe Troin wrote:
> 
> Hi Philippe,
> 
> > Marc-Christian Petersen <m.c.p@wolk-project.de> writes:
> > > On Wednesday 15 October 2003 17:40, Christoph Pleger wrote:
> > >
> > > Hi Christoph,
> > >
> > > > I am using a 2.4.22 kernel from www.kernel.org together with an XFS
> > > > patch from SGI. I want to use LVM for creating snapshots for backups,
> > > > but I found out that I cannot mount the snapshots of journalling
> > > > filesystems (EXT3, XFS, Reiser). Only JFS snapshots can be mounted.
> > > > My research on internet gave the result that a kernel-patch must be
> > > > used to solve that problem, but I could not find such a patch for Linux
> > > > 2.4.22, so where can I get it?
> > >
> > > Marcelo decided not to apply that needed patch. Here it is for you to
> > > play with :) ... It'll apply with offsets to 2.4.23-pre7.
> >
> > What was the reason? I cannot find this thread in the archives...
> 
> it was a private mail. Pasting relevant stuff:
> 
> ---------------------------------------------------------------------
> > - [PATCH 2.4.23-pre1] LVM 1.0.7 ADDON: Allow snapshots on journaling
> >                                        filesystems
> 
> LVM has already been updated on 2.4.23-pre. Lets do more changes later on.
> 
> ---------------------------------------------------------------------

Nothing technical then, Marcelo is just being slow for stability's
sake and easier testing. I guess that will go in somewhere in a later
23-pre or in 24.

Thanks for the info.

Phil.

Re: LVM Snapshots

[Marcelo Tosatti]

On Wed, 15 Oct 2003, Marc-Christian Petersen wrote:

> On Wednesday 15 October 2003 17:40, Christoph Pleger wrote:
> 
> Hi Christoph,
> 
> > I am using a 2.4.22 kernel from www.kernel.org together with an XFS
> > patch from SGI. I want to use LVM for creating snapshots for backups,
> > but I found out that I cannot mount the snapshots of journalling
> > filesystems (EXT3, XFS, Reiser). Only JFS snapshots can be mounted.
> > My research on internet gave the result that a kernel-patch must be used
> > to solve that problem, but I could not find such a patch for Linux
> > 2.4.22, so where can I get it?
> 
> Marcelo decided not to apply that needed patch. Here it is for you to play 
> with :) ... It'll apply with offsets to 2.4.23-pre7.

Because the patch touches generic fs code.

Dont use LVM with XFS for now.

Re: LVM Snapshots

[Christoph Pleger]

ello,

On Fri, 17 Oct 2003 09:12:30 -0200 (BRST)
Marcelo Tosatti <marcelo.tosatti@cyclades.com> wrote:


> > > I am using a 2.4.22 kernel from www.kernel.org together with an
> > > XFS patch from SGI. I want to use LVM for creating snapshots for
> > > backups, but I found out that I cannot mount the snapshots of
> > > journalling filesystems (EXT3, XFS, Reiser). Only JFS snapshots
> > > can be mounted. My research on internet gave the result that a
> > > kernel-patch must be used to solve that problem, but I could not
> > > find such a patch for Linux 2.4.22, so where can I get it?
> > 
> > Marcelo decided not to apply that needed patch. Here it is for you
> > to play with :) ... It'll apply with offsets to 2.4.23-pre7.
> 
> Because the patch touches generic fs code.
> 
> Dont use LVM with XFS for now.

I have used them together. The only thing that made problems at first
after applying the LVM-patch was that I did not know that the special
option "nouuid" is needed when mounting an XFS-Snapshot. But afterwards
I had no problem so far. 

So why do you think that I should not use XFS on a logical volume?

Christoph

Re: LVM Snapshots

[Marcelo Tosatti]

On Fri, 17 Oct 2003, Christoph Pleger wrote:

> ello,
> 
> On Fri, 17 Oct 2003 09:12:30 -0200 (BRST)
> Marcelo Tosatti <marcelo.tosatti@cyclades.com> wrote:
> 
> 
> > > > I am using a 2.4.22 kernel from www.kernel.org together with an
> > > > XFS patch from SGI. I want to use LVM for creating snapshots for
> > > > backups, but I found out that I cannot mount the snapshots of
> > > > journalling filesystems (EXT3, XFS, Reiser). Only JFS snapshots
> > > > can be mounted. My research on internet gave the result that a
> > > > kernel-patch must be used to solve that problem, but I could not
> > > > find such a patch for Linux 2.4.22, so where can I get it?
> > > 
> > > Marcelo decided not to apply that needed patch. Here it is for you
> > > to play with :) ... It'll apply with offsets to 2.4.23-pre7.
> > 
> > Because the patch touches generic fs code.
> > 
> > Dont use LVM with XFS for now.
> 
> I have used them together. The only thing that made problems at first
> after applying the LVM-patch was that I did not know that the special
> option "nouuid" is needed when mounting an XFS-Snapshot. But afterwards
> I had no problem so far. 
> 
> So why do you think that I should not use XFS on a logical volume?

Because the filesystem code lacks locking somewhere (thats what the 
patches adds). 

It seems its not safe to create snapshots of journalled fs'es without this
patch.