Re: [User Question] How to create a backup of an LVM based maschine without wasting space

[Lukas Laukamp <lukas@laukamp.me>]

Am 12.10.2012 16:36, schrieb Javier Guerra Giraldez:
> On Fri, Oct 12, 2012 at 9:25 AM, Stefan Hajnoczi <stefanha@gmail.com> wrote:
>> I would leave them raw as long as they are sparse (zero regions do not
>> take up space).  If you need to copy them you can either convert to
>> qcow2 or use tools that preserve sparseness (BTW compression tools are
>> good at this).
> note that free blocks previously used by deleted files won't be
> sparse, won't be zero and won't be much reduced by compression.
>
> i'd say the usual advice stays:
>
> A: if you run any non-trivial application on that VM, then use a real
> network backup tool 'from the inside' of the VM
> B: if real point-in-time application-cache-storage consistency is not
> important, then you can:
>
> - make a read-write LVM snapshot
> - mount that and fsck.  (it will appear as not-cleanly unmounted)
> - backup the files. (i like rsync, especially if you have an
> uncompressed previous backup)
> - umount and destroy the snapshot
> - optionally compress the backup
>
>
> but seriously consider option A before.  especially important if you
> run any DB on that VM
>

I already thought about such situations. So DB systems are a real 
problem. I know that some data can be better backup directly but for 
example a VM for a Web- or Mailserver I want to backup completely to get 
this services get to work again very fast if there are problems. So it's 
a complex problem I think and not every machine can be backuped as another.

I think that I must start by the hardware and software configuration of 
the backup node.

Best Regards