[linux-lvm] Snapshot rollback

[linux-lvm] Snapshot rollback

[Eric Brunson]

I remember seeing somewhere discussion of adding the ability to roll 
back to a snapshot.  I think of how cool this would be about ever six 
months, usually coinciding with an impending Fedora release.  ;-)

I know it's possible to copy the snapshot to restore the data, but what 
would it take to simply "abandon" the modified blocks and revert the 
volume to the snapshot state?  Is it being worked on?  Can I help?

Thanks,
e.

Re: [linux-lvm] Snapshot rollback

[Brian J. Murrell]

[-- Attachment #1: Type: text/plain, Size: 413 bytes --]

On Wed, 2009-09-23 at 15:04 -0600, Eric Brunson wrote: 
> I remember seeing somewhere discussion of adding the ability to roll 
> back to a snapshot.

http://www.archivum.info/linux-lvm@redhat.com/2007-09/00020/%5Blinux-lvm
%5D_collapse_(merge)_snapshot_into_origin

> I think of how cool this would be about ever six 
> months, usually coinciding with an impending Fedora release.  ;-)

Yeah.

b.


[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 197 bytes --]

Re: [linux-lvm] Snapshot rollback

[Alasdair G Kergon]

On Wed, Sep 23, 2009 at 03:04:22PM -0600, Eric Brunson wrote:
> I remember seeing somewhere discussion of adding the ability to roll  
> back to a snapshot.  I think of how cool this would be about ever six  
> months, usually coinciding with an impending Fedora release.  ;-)

The developers are just starting to submit their patch sequence to the
development mailing lists (dm-devel and lvm-devel) for review.  So
that's targetting linux-next in the next few weeks ready for the 2.6.33
kernel.

Alasdair

Re: [linux-lvm] Snapshot rollback

[Eric Brunson]

On 09/23/2009 03:40 PM, Alasdair G Kergon wrote:
> On Wed, Sep 23, 2009 at 03:04:22PM -0600, Eric Brunson wrote:
>    
>> I remember seeing somewhere discussion of adding the ability to roll
>> back to a snapshot.  I think of how cool this would be about ever six
>> months, usually coinciding with an impending Fedora release.  ;-)
>>      
> The developers are just starting to submit their patch sequence to the
> development mailing lists (dm-devel and lvm-devel) for review.  So
> that's targetting linux-next in the next few weeks ready for the 2.6.33
> kernel.
>    

That is very, very cool news.  Thanks!

Re: [linux-lvm] Snapshot rollback

[Eric Brunson]

On 09/23/2009 03:29 PM, Brian J. Murrell wrote:
> On Wed, 2009-09-23 at 15:04 -0600, Eric Brunson wrote:
>    
>> I remember seeing somewhere discussion of adding the ability to roll
>> back to a snapshot.
>>      
> http://www.archivum.info/linux-lvm@redhat.com/2007-09/00020/%5Blinux-lvm
> %5D_collapse_(merge)_snapshot_into_origin
>
>    
>

That's what I saw.  Thanks, I couldn't find the link.  :-)

Re: [linux-lvm] Snapshot rollback

[Eric Brunson]

[-- Attachment #1: Type: text/plain, Size: 1963 bytes --]

On 09/23/2009 03:40 PM, Alasdair G Kergon wrote:
> On Wed, Sep 23, 2009 at 03:04:22PM -0600, Eric Brunson wrote:
>    
>> I remember seeing somewhere discussion of adding the ability to roll
>> back to a snapshot.  I think of how cool this would be about ever six
>> months, usually coinciding with an impending Fedora release.  ;-)
>>      
> The developers are just starting to submit their patch sequence to the
> development mailing lists (dm-devel and lvm-devel) for review.  So
> that's targetting linux-next in the next few weeks ready for the 2.6.33
> kernel.
>
>    

 From the newly released 2.6.33 kernel changelog, does this mean what I 
think it means?

    commit 53365383c4667aba55385cd1858582c19a7a8a36
    Merge: 51b736b d2fdb77
    Author: Linus Torvalds<torvalds@linux-foundation.org>
    Date:   Tue Dec 15 09:12:01 2009 -0800

         Merge git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dm

         * git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dm: (80 commits)
           dm snapshot: use merge origin if snapshot invalid
           dm snapshot: report merge failure in status
           dm snapshot: merge consecutive chunks together
           dm snapshot: trigger exceptions in remaining snapshots during merge
           dm snapshot: delay merging a chunk until writes to it complete
           dm snapshot: queue writes to chunks being merged
           dm snapshot: add merging
           dm snapshot: permit only one merge at once
           dm snapshot: support barriers in snapshot merge target
           dm snapshot: avoid allocating exceptions in merge
           dm snapshot: rework writing to origin
           dm snapshot: add merge target
           dm exception store: add merge specific methods
           dm snapshot: create function for chunk_is_tracked wait
           dm snapshot: make bio optional in __origin_write
           ...
       


If it does, then I'm very excited.  :-)

e.


[-- Attachment #2: Type: text/html, Size: 2435 bytes --]

Re: [linux-lvm] Snapshot rollback

[Mike Snitzer]

On Wed, Feb 24 2010 at  5:46pm -0500,
Eric Brunson <brunson@brunson.com> wrote:

> On 09/23/2009 03:40 PM, Alasdair G Kergon wrote:
> >On Wed, Sep 23, 2009 at 03:04:22PM -0600, Eric Brunson wrote:
> >>I remember seeing somewhere discussion of adding the ability to roll
> >>back to a snapshot.  I think of how cool this would be about ever six
> >>months, usually coinciding with an impending Fedora release.  ;-)
> >The developers are just starting to submit their patch sequence to the
> >development mailing lists (dm-devel and lvm-devel) for review.  So
> >that's targetting linux-next in the next few weeks ready for the 2.6.33
> >kernel.
> >
> 
> From the newly released 2.6.33 kernel changelog, does this mean what
> I think it means?
> 
>    commit 53365383c4667aba55385cd1858582c19a7a8a36
>    Merge: 51b736b d2fdb77
>    Author: Linus Torvalds<torvalds@linux-foundation.org>
>    Date:   Tue Dec 15 09:12:01 2009 -0800
> 
>         Merge git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dm
> 
>         * git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-2.6-dm: (80 commits)
>           dm snapshot: use merge origin if snapshot invalid
>           dm snapshot: report merge failure in status
>           dm snapshot: merge consecutive chunks together
>           dm snapshot: trigger exceptions in remaining snapshots during merge
>           dm snapshot: delay merging a chunk until writes to it complete
>           dm snapshot: queue writes to chunks being merged
>           dm snapshot: add merging
>           dm snapshot: permit only one merge at once
>           dm snapshot: support barriers in snapshot merge target
>           dm snapshot: avoid allocating exceptions in merge
>           dm snapshot: rework writing to origin
>           dm snapshot: add merge target
>           dm exception store: add merge specific methods
>           dm snapshot: create function for chunk_is_tracked wait
>           dm snapshot: make bio optional in __origin_write
>           ...
> 
> 
> If it does, then I'm very excited.  :-)

Ha, yes the 2.6.33 kernel includes DM's new snapshot-merge target.

LVM2 >= 2.02.59 provides userspace support for snapshot-merge (via
lvconvert --merge).  Though 2.02.61 adds the ability to tag N snapshots
with a common tag and then merge them all back to their respective
origin using: lvconvert --merge @tag

Mike