[Xen-users] Re: 100% safe way to backup domU: (was Yet another backup)

["Ulrich Windl" <ulrich.windl@xxxxxxxxxxxxxxxxxxxx>]

On 12 Jan 2007 at 2:09, Ligesh wrote:

[...]
>  I forgot about the 'save' feature. If we have a consistent file system that 
> can be mounted and backed up, and if we add the ram separately, the we have 
> the entire state of the system. So I think the actual steps would be.
> 
>  xm sync-and-save domU file

Complete overkill IMHO: When having a say 8GB virtual RAM DomU, saving of the 
virtual RAM takes a very long time (several minutes).

>  take lvm snapshot
>  xm restore file
>  backup snapshot + file
> 
> 
>   Backing up the all the domUs live from the dom0 is an extremely
> important feature. In the hosting industry, taking down the server for
> getting a task done is not an idea that people can even understand, let
> alone accept. 

Actually I believe that in a HA environment where several related files are 
used 
to store some state, a transactional database should be used instead. You are 
fighting symptoms, not the bugs. If strong time-relationship of file contents 
is 
not necessary, a plain backup (full or incremental) would be sufficient.

You are talking about desaster recovery: A desaster by definition is something 
noticable. When planning for desaster, why care about varying point-in-time 
backups, when you actually may loose several hours of data?

For the non-desaster: Just restore the last (or any other) saved version of the 
file desired to be restored.

Regards,
Ulrich


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