Xen users - Aug 2011 - newbie questions: copying and cloning xen vm

Hi all,

I started studying xen to implement some HA cluster hosting multiple guests.
I am realizing that xen does not provide any native way to hot-clone or
hot-backup a guest.

Am I right ?

Is there any way to how backup a virtual machine? Or is suspend - copy  -
resume the only possible tecnique ?
Is there any way to clone a virtual machine?
Do vm snapshots exists?

Thank you for every answer!

Andrea


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Hi Andrea,

You can see the manpage of xen-create-image:
http://man.cx/xen-create-image%288%29, I believe you are search a command
like this...

Regards,

Diego

2011/8/11 Andrea Monti <ilsuonogiallo@gmail.com>
> Hi all,
>
> I started studying xen to implement some HA cluster hosting multiple
> guests.
> I am realizing that xen does not provide any native way to hot-clone or
> hot-backup a guest.
>
> Am I right ?
>
> Is there any way to how backup a virtual machine? Or is suspend - copy  -
> resume the only possible tecnique ?
> Is there any way to clone a virtual machine?
> Do vm snapshots exists?
>
> Thank you for every answer!
>
> Andrea
>
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
>

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Hi Diedo,

thank you for your input.
Unfortunatly xen-create-image is part of xen tools, so it is only available
on Debian.
I am using Xen 3.4 on Oracle VM, so I don''t have xen-tools available :
that''s why I am looking for "native" xen tools to copy /
clone / backup my
vms.

Regards,
Andrea

2011/8/11 Diego Dave <diego.dave.s@gmail.com>
> Hi Andrea,
>
> You can see the manpage of xen-create-image:
> http://man.cx/xen-create-image%288%29, I believe you are search a command
> like this...
>
> Regards,
>
> Diego
>
> 2011/8/11 Andrea Monti <ilsuonogiallo@gmail.com>
>
>> Hi all,
>>
>> I started studying xen to implement some HA cluster hosting multiple
>> guests.
>> I am realizing that xen does not provide any native way to hot-clone or
>> hot-backup a guest.
>>
>> Am I right ?
>>
>> Is there any way to how backup a virtual machine? Or is suspend - copy 
-
>> resume the only possible tecnique ?
>> Is there any way to clone a virtual machine?
>> Do vm snapshots exists?
>>
>> Thank you for every answer!
>>
>> Andrea
>>
>>
>> _______________________________________________
>> Xen-users mailing list
>> Xen-users@lists.xensource.com
>> http://lists.xensource.com/xen-users
>>
>
>

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On Fri, Aug 12, 2011 at 3:04 PM, Andrea Monti <ilsuonogiallo@gmail.com>
wrote:
> Hi Diedo,
>
> thank you for your input.
> Unfortunatly xen-create-image is part of xen tools, so it is only available
> on Debian.
> I am using Xen 3.4 on Oracle VM, so I don''t have xen-tools
available :
> that''s why I am looking for "native" xen tools to copy /
clone / backup my
> vms.
"native" is somewhat tricky. The only common part in XenServer/XCP and
xen (the hypervisor used by linux distros) is basically just the
hypervisor. Even the userland tools can be different (xe vs xm/xl).

The hypervisor by itself doesn''t really have anything to do with
"hot-clone" or "hot-backup". That functionality is
implemented in:
- OS driver/additions (if any) id domU, that would ensure all data is
flushed to disk before the snapshot
- domU backing storage that is capable of doing snapshot/clone (e.g.
LVM, VHD image)

So the short version to your question, the closest thing to what you
want is to probably do a LVM-snapshot on dom0, use the snapshot data
to create a clone, then delete the snapshot afterwards. If your
backing storage is capable of creating "good" clones (e.g. zfs,
netapp) then you could use that directly.

-- 
Fajar

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2011/8/12 Fajar A. Nugraha <list@fajar.net>
> On Fri, Aug 12, 2011 at 3:04 PM, Andrea Monti
<ilsuonogiallo@gmail.com>
> wrote:
> > Hi Diedo,
> >
> > thank you for your input.
> > Unfortunatly xen-create-image is part of xen tools, so it is only
> available
> > on Debian.
> > I am using Xen 3.4 on Oracle VM, so I don''t have xen-tools
available :
> > that''s why I am looking for "native" xen tools to
copy / clone / backup
> my
> > vms.
>
> "native" is somewhat tricky. The only common part in
XenServer/XCP and
> xen (the hypervisor used by linux distros) is basically just the
> hypervisor. Even the userland tools can be different (xe vs xm/xl).
>
> The hypervisor by itself doesn''t really have anything to do with
> "hot-clone" or "hot-backup". That functionality is
implemented in:
> - OS driver/additions (if any) id domU, that would ensure all data is
> flushed to disk before the snapshot
> - domU backing storage that is capable of doing snapshot/clone (e.g.
> LVM, VHD image)
>
> So the short version to your question, the closest thing to what you
> want is to probably do a LVM-snapshot on dom0, use the snapshot data
> to create a clone, then delete the snapshot afterwards. If your
> backing storage is capable of creating "good" clones (e.g. zfs,
> netapp) then you could use that directly.
>
> --
> Fajar
>
>
>
Hi Fajar,
Thanks for your explanations!

I managed to use logical volumes as guests partition, so I can use
LVM-snapshot on dom0 to do hot-backups of my VMs and I use nested lvm on
domU to manage disks and partitions.

Andrea


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Andrea Monti wrote:
>I managed to use logical volumes as guests partition, so I can use 
>LVM-snapshot on dom0 to do hot-backups of my VMs and I use nested 
>lvm on domU to manage disks and partitions.
Just as long as you realise that your "backups" are in fact almost 
certainly corrupted to some extent or other. Wether that is an issue 
for you depends heavily on the type of operations your DomU does. If 
it''s "write-little" and has journalled filesystems then
it''s probably
not serious. If it''s "write-heavy", and especially if it runs
applications that do their own caching (like DBs), then it could be 
more serious.

Your snapshot has a state somewhat akin to what you''d have if you 
just yanked the power cord on a bare-metal server.

-- 
Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.

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