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

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

[Mark Bainter]

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

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

[Iain Campbell]

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??

iain

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

[Heinz J . Mauelshagen]

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 ***

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

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

Re: [linux-lvm] Some ideas regarding snapshots (was: Reiserfs, 2.4.7, snapshots w/ 0.9)

[Wolfgang Weisselberg]

Iain Campbell (iain@sandon.ca) wrote 64 lines:
> Quote from Teigland and Mauelshagens's Volume Manager whitepaper:

> journalled file system. These operations (fsck or journal replay) require 
> writing to  the snapshot ligical volume, which is not allowed."

On a related subject: would it be possible to have a writable
snapshot (probably a 'reverse' snapshot)?

I remember a few situations where I would have done a lot for
a feature like that; e.g. building a system that's 'guaranteed'
the same after restarting/rebooting it.

The idea is along the lines of:
- you have the system in a known good, fscked state on the HD.
- you snapshot that (possibly huge) system
- you mount the snapshots r/w
- the original will probably stay unmounted or r/o (but not
  neccessarily, I am thinking of robust, networked stand-alone
  devices which could be upgraded in the background while
  running; a simple restart will have the upgrade applied.)
- The system can scribble onto the snapshots until they
  are full.
- To reset the complete system to the known good state, umount,
  unsnapshot, start over.  Or even -- horror -- reboot.

This should be *much* faster than a reintarnation or the use
of dd, not to mention easier, simpler, more elegant and using
less space.


And on another related idea: can we have the option of making
snapshots non-persistant again?  Or is that lots of work?
There sometimes are cases where snapshots lose all value over
a reboot, so they could/should automagically disappear.

-Wolfgang

Re: [linux-lvm] Some ideas regarding snapshots (was: Reiserfs, 2.4.7, snapshots w/ 0.9)

[Joe Thornber]

On Thu, Jul 26, 2001 at 01:55:14PM +0200, Wolfgang Weisselberg wrote:
> Iain Campbell (iain@sandon.ca) wrote 64 lines:
> > Quote from Teigland and Mauelshagens's Volume Manager whitepaper:
> 
> > journalled file system. These operations (fsck or journal replay) require 
> > writing to  the snapshot ligical volume, which is not allowed."
> 
> On a related subject: would it be possible to have a writable
> snapshot (probably a 'reverse' snapshot)?

Writeable snapshot's are easy to implement, I believe someone has
already made a patch for the current LVM series (search the list).  I
certainly intend putting it into the experimental LVM branch soon.

- Joe

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

[Heinz J . Mauelshagen]

Mark,

Chris Mason implemented an interface between the VFS and LVM, which is defined
by 2 new functions VFS functions. They have to be supported in the filesystem
itself in order to flush the journal and lock the filesystem for I/O, get
back to LVM so that it can activate the prepared snapshot. LVM unlocks the
filesystem after this.
You pay a (small) I/O penalty for the journal flush.

Because those functions are not in vanilla, you still need to patch the
kernel with the linux-2.4.X-VFS-lock-patch contained in the LVM distribution :-(

That patch will enable the above feature after a kernel recompile/reboot.


On Wed, Jul 25, 2001 at 10:36:40AM -0500, Mark Bainter 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

-- 

Regards,
Heinz    -- The LVM Guy --

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

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

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

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

[José Luis Domingo López]

On Wednesday, 25 July 2001, at 21:44:51 +0200,
Heinz J . Mauelshagen wrote:

> 
> Mark,
> 
> Chris Mason implemented an interface between the VFS and LVM, which is defined
> by 2 new functions VFS functions. They have to be supported in the filesystem
> itself in order to flush the journal and lock the filesystem for I/O, get
> back to LVM so that it can activate the prepared snapshot. LVM unlocks the
> filesystem after this.
> You pay a (small) I/O penalty for the journal flush.
> 
> Because those functions are not in vanilla, you still need to patch the
> kernel with the linux-2.4.X-VFS-lock-patch contained in the LVM distribution :-(
> 
Does it mean that, to support XFS snapshots you need to apply the patch ?.
http://linuxtoday.com/news_story.php3?ltsn=2001-07-11-011-20-NW-SW

This announcement says XFS 1.0.1 has "LVM snapshotting capability added",
but it says nothing about additional kernel patches required.

Could you clarify please ?.

--
Jos� Luis Domingo L�pez
Linux Registered User #189436     Debian GNU/Linux Potato (P166 64 MB RAM)
 
jdomingo EN internautas PUNTO org  => � Spam ? Atente a las consecuencias
jdomingo AT internautas DOT   org  => Spam at your own risk

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

[Gonyou, Austin]

So does that mean that the VFS patches are ONLY for snapshotting?

-- 
Austin Gonyou
Systems Architect, CCNA
Coremetrics, Inc.
Phone: 512-796-9023
email: austin@coremetrics.com 

> -----Original Message-----
> From: Heinz J . Mauelshagen [mailto:mauelshagen@sistina.com]
> Sent: Wednesday, July 25, 2001 2:45 PM
> To: linux-lvm@sistina.com
> Subject: Re: [linux-lvm] Reiserfs, 2.4.7, snapshots w/ 0.9
> 
> 
> 
> Mark,
> 
> Chris Mason implemented an interface between the VFS and LVM, 
> which is defined
> by 2 new functions VFS functions. They have to be supported 
> in the filesystem
> itself in order to flush the journal and lock the filesystem 
> for I/O, get
> back to LVM so that it can activate the prepared snapshot. 
> LVM unlocks the
> filesystem after this.
> You pay a (small) I/O penalty for the journal flush.
> 
> Because those functions are not in vanilla, you still need to 
> patch the
> kernel with the linux-2.4.X-VFS-lock-patch contained in the 
> LVM distribution :-(
> 
> That patch will enable the above feature after a kernel 
> recompile/reboot.
> 
> 
> On Wed, Jul 25, 2001 at 10:36:40AM -0500, Mark Bainter 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
> 
> -- 
> 
> Regards,
> Heinz    -- The LVM Guy --
> 
> *** Software bugs are stupid.
>     Nevertheless it needs not so stupid people to solve them ***
> 
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> =-=-=-=-=-=-=-=-
> 
> Heinz Mauelshagen                                 Sistina 
> Software Inc.
> Senior Consultant/Developer                       Am Sonnenhang 11
>                                                   56242 Marienrachdorf
>                                                   Germany
> Mauelshagen@Sistina.com                           +49 2626 141200
>                                                        FAX 924446
> =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
> =-=-=-=-=-=-=-=-
> _______________________________________________
> 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
>