Xen users - May 2012 - domU backup strategy

I''m looking for efficient backup method of all domUs. I''ve
searched the group and googled for perfect backup solution - without good enough
results.

My configuration is following (PV):
3 zones: FW, DMZ, LOC

dom0 in LOC minimal config, only hypervisor
domU1 as FW with OpenVPN running
domU2 in DMZ with external services
domU3 in LOC with local services

All domains run with LVM. I can afford for some downtime during the night to
make consistent snapshots. Domains are reasonably small < 10 GB. Presumably
domU3 will have DB partition growing ~150MB / week.
Now, dom0 won''t have an acces to the Internet when domU1 is down.
However, I can reconfigure interface on dom0 when doing backup - but I
don''t want dom0 to have direct access to the net.

Therefore, the idea would be to keep snapshots in separate logical volumes and
then mount them to additional domain that will send them to NFS attached with
VPN. This solution would require 2x disk space, assuming that volumes would be
copied and other domains already running.
I can keep them stopped and then send the snapshots via NFS, but this would
increase the downtime significantly.

By copied I mean rsynced :)
I plan to backup dom0 by making LVM snapshot on unmounted system. 

How it can be done better ?

Slawomir Kosowski

On 17/05/2012 09:44, Sławek Kosowski wrote:
> I'm looking for efficient backup method of all domUs. I've searched
the group and googled for perfect backup solution - without good enough results.
>
> My configuration is following (PV):
> 3 zones: FW, DMZ, LOC
>
> dom0 in LOC minimal config, only hypervisor
> domU1 as FW with OpenVPN running
> domU2 in DMZ with external services
> domU3 in LOC with local services
>
> All domains run with LVM. I can afford for some downtime during the night
to make consistent snapshots. Domains are reasonably small<  10 GB.
Presumably domU3 will have DB partition growing ~150MB / week.
> Now, dom0 won't have an acces to the Internet when domU1 is down.
However, I can reconfigure interface on dom0 when doing backup - but I don't
want dom0 to have direct access to the net.
>
> Therefore, the idea would be to keep snapshots in separate logical volumes
and then mount them to additional domain that will send them to NFS attached
with VPN. This solution would require 2x disk space, assuming that volumes would
be copied and other domains already running.
> I can keep them stopped and then send the snapshots via NFS, but this would
increase the downtime significantly.
>
> By copied I mean rsynced :)
> I plan to backup dom0 by making LVM snapshot on unmounted system.
>
> How it can be done better ?
>
> Slawomir Kosowski
Generally, my "rule of thumb" is to just take a snapshot of the
running
DomU and rsync it to the destination. No downtime required. I completely 
ignore consistency issues, except where it is really important. For 
example, if a DomU runs a database, I also run an additional backup 
method (eq SQL dump from within the DomU).

Hope this makes sense

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>I''ve searched the group and googled for perfect backup solution
There is no such thing.

You''ll see there have been a couple of "fairly vigorous"
discussion
of the subject in this list. Look for a thread called "Backup domU" 
from July last year - I think everything was "well discussed" then.

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