Re: [Xen-users] snapshot - backup for xen vm's

[Nico Kadel-Garcia <nkadel@xxxxxxxxx>]

Fajar A. Nugraha wrote:
> Nico Kadel-Garcia wrote:
>   
> > Fajar A. Nugraha wrote:
> >     
> > > it-news (Josef Lahmer) wrote:
> > >  
> > >       
> > > > is there a way to make a lvm-snapshot of an running xen-vm to
> > > > implement a function like "snapshot-backup"?
> > > >
> > > >         
> [snip]
>   
> > > If you :
> > > - use an LV (NOT files) on dom0 as storage for domU's block device
> > > - use partitions on domU (NOT LVM)
> > >
> > > Then both link are applicable right away
> > >       
> [snip]
>   
> > Unfortunately, that piece of over-hyped installatiion obscurity known
> > as libvirt does not allow you options to do this, and mandates the use
> > of pygrub. This means that you must have a /dev/xdva device, and grub
> > itself only works if you have a disk, not if you only have partitions.
> >     
> pygrub works perfectly with partition-only setup (at least on RHEL5).
> You could take a virt-manager-based installation, copy the files to
> partition-only-domU setup, modify grub.conf and fstab, and have a
> working system.
>
> I know this seems like an extra unnecessary step (install-copy-modify
> instead of just install). Which is why my prefered method is to create a
> template (in tar.gz, with some host-specific stuff like ssh host key
> removed), so the next "installation" can simply be a tar xvfz.
>   
It is a painful extra step. Pygrub doesn't read the MBR off of the 
para-virtualized image?
I've used the "jailtime" tarballs for CentOS: they're fairly reasonable, 
but are cluttered with disk images rather than simply providing a 
tarball and letting the installer set up their own partitions.
> >  It's also very, very helpful to have enough disk in the partiton to
> > mirror the *whole* RedHat or Fedora installation directory. 
> >     
> I'm not sure what you mean here. I'd prefer to have a local copy of yum
> repository (including RH installation directory). It's on local network,
> accessed via http, but it doesn't have to be on dom0. That way it scales
> well if you have lots of dom0s.
>
> Regards,
>
> Fajar
>   
Mirror the whole RedHat DVD or network install site. Copy it to local 
disk on the domain creating machine: you want this all to happen on 
local disk, *NOT* over a network! Make a new partition, and mount it. 
Copy the whole thing over to /var/cache/yum/base/packages and work from 
there to install whatever you want, usually with yum. Do an alternative 
root directory RPM or Yum installation into that directory. But using 
yum, it downloads the files: it's vastly faster to simply copy them over 
and use a "file:///" based URL, rather than the classic HTTP or FTP 
URL's. be already available or wind up downloaded into /var/cache/yum in 
the target directory, but you have a huge advantage in being able to do 
the updates or add-on packages at OS image install time, rather than 
wending your way through
Some folks try to set up teeny-tiny little Xen partitions for firewalls 
or other resource limited setups, so they might not have the space to do 
this stunt comfortably.
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