Re: [linux-lvm] Reiserfs, 2.4.7, snapshots w/ 0.9

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

On Wed, Jul 25, 2001 at 11:46:57AM -0400, Iain Campbell wrote:
> On Wednesday 25 July 2001 11:36, you wrote:
> > I'm using LVM on a couple of our production systems, and I'm very
> > happy with it.  It's been working very well for us.  However, we
> > have a very large database and backing it up has become problematic.
> >
> > So, naturally, I began looking into using LVM's snapshot feature.
> > The filesystem the database rests on is a reiserfs partition.
> > Creating the snapshot volume (acc to the directions in the howto)
> > works fine, but when I try to actually mount it I get:
> >
> > $ sudo mount -t reiserfs -oro /dev/main/db_backup /mnt/dbbackup
> > mount: wrong fs type, bad option, bad superblock on /dev/main/db_backup,
> >        or too many mounted file systems
> >
> > checking dmesg reveals:
> > reiserfs: checking transaction log (device 3a:04) ...
> > clm-2076: device is readonly, unable to replay log
> > Replay Failure, unable to mount
> > reiserfs_read_super: unable to initialize journal space
> >
> > Ok, so I did some searching and found some people back in the first
> > part of this year had a similar problems but none of the solutions
> > really applied to me fwict.  They all appeared to be using a
> > previous version of the kernel, or of the lvm code.  I looked through
> > the changelog and did see a few notations of fixes since 0.9 related
> > to the snapshot code.  But, I'm kind of wary about putting a beta
> > on my production systems with something this critical, w/out knowing
> > for sure that it will fix the problem.
> >
> > So, is the problem in lvm?  reiserfs?  Or is it just me?  Is there
> > any other information I can give that might be helpfull in figuring
> > out the problem?  Just let me know.
> >
> > TIA
> > _______________________________________________
> > linux-lvm mailing list
> > linux-lvm@sistina.com
> > http://lists.sistina.com/mailman/listinfo/linux-lvm
> > read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html
> 
> Quote from Teigland and Mauelshagens's Volume Manager whitepaper:
> 
> "If a snapshot is simply taken of a file system volume, the resulting copy of 
> the file system will look as if the system has crashed.  When the snapped 
> file system is then mounted read only it would appear to need an fsck, in the 
> case of a non journalled file system, or journal recovery in the case of  a 
> journalled file system. These operations (fsck or journal replay) require 
> writing to  the snapshot ligical volume, which is not allowed."
> 
> There's more, get the whole thing from sistina.com/lvm. Look for 
> vmil_freenix.pdf.
> 
> Question to Heinz - what is the status of getting file system snapshot hooks 
> into the kernel??

Have forwarded that to Chris Mason who created the VFS interface.

> 
> iain
> 
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html

-- 

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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