Re: [Xen-users] FAQ: How to backup for recovery?

["Christoph Purrucker" <cp+ml-xen@xxxxxxxx>]

Hi Ulrich,

> DomUs can be backed up just fine, and there's no problem to restore files
> as long
> as the DomU boots. Now I wonder how to recover hard (desaster recovery)...
> Backing up the disk images or partitions (from Dom0) seems to be not an
> option,
> because there are changes to them all the time, so incremental backups
> would always save them, and all saves would be inconsistent.

I'm using LVM for DomUs: On backup time, I create a LVM snapshot, mount
the snapshot in Dom0 and running rdiff-backup to create a new increment.
On desaster, I create a new logical volume and restore the rdiff-backup
into the mounted volume after creating a filesystem in the new LV. Now you
can umount the volume and startup the DomU.

> Now the idea is this: Provide a tool that extracts the "structure of a
> partition
> or image file" into some data file or script that can be used to recrerate
> that
> container later. Then my idea was to loop-mount the thing (yet unsure how
> to do
> that for partitions and files that are "harddisks" for DomU), and restore
> the backup to those.

You may create a snapshot, and dd it somewhere to s save place. But there
are two disadvantages:

- This needs a lot of backup space
- You can't recover from hidden filesystem corruptions

> Maybe a "mini-root" (rescue system) as tar archive would be helpful as
> well. I'd like to see these issues discussed at least in the docs.

I tar Dom0. Since it has a very small footprint this is the ideal rescue
system for me.

Gruß,
cp

-- 
Die Homepage meines Vertrauens: www.cpur.de


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