[Libvir] [RFC] Life-cycle Management of the domain

Daniel Veillard veillard at redhat.com
Wed Apr 18 18:08:37 UTC 2007

On Tue, Apr 17, 2007 at 02:38:26PM +0900, Saori Fukuta wrote:
> Hi,
> What the following things boil down to is that 
> I hold file that formed in SXP for Life-cycle Management.
> What do you think of my idea?

  That I not too fond of adding ome more place where data for domain
definition can be stored.

> Thanks
> Saori Fukuta
> On Fri, 13 Apr 2007 16:26:37 +0900 Saori Fukuta wrote:
> > Hi all,
> > 
> > I've been thinking about a way to change the hardware allocation on the 
> > Life-cycle. And I have some idea. Can I hear your comments about this?
> > 
> > 1. Necessity of function
> > These are conceivable cases of changing hardware allocation.
> > 
> >     CASE A: Dynamic change
> >             change the allocation dynamically
> >             -> change the hardware allocation for now, 


> >                and next time, start by the allocation before it changes.

  that would have to be done using the API

> >     CASE B: Static change
> >             change the allocation statically
> >             -> do not change the hardware allocation for now, 
> >                but set the allocation for starting next.
> >             (example of use)
> >             Next time, want to start by the value that set before.

  We can't know what are the original data which were used to create the domain
was that /etc/xen/... ? was that an XML file coming from a client application ?
was that another source by calling the Xen API ? We can't know, we can't 
modify the original data, and I don't think it's wise to try to keep extra
data "somewhere" which would only be seen by libvirt or virsh and which would
modify the original data. I don't think this has its place in libvirt or
virsh, but what we must make sure is that the API allow to make the required
change dynamically.

> >     CASE C: Permanent change 
> >             change the allocation permanently
> >             -> change the hardware allocation,
> >                and start next time with the same setting.
> >             (example of use)
> >             want to start by same value permanently.

  Same thing, we can't know where the original data used to create a domain are.
How do you want to modify it ?
  For example if I use a python script with the XML docmain definition in 
the script, you can't guess where it is, you can't change it, I think hoping
to be able to do that or override it is a wrong approach. Either you 
succeed and suddenly from the application point of view the API is not 
reliable anymore or you won't succeed and it's probably not a good idea
to suggest it.

  So I'm a bit puzzled by what you actually intent to do. In a management
framework you can change things because you're supposed to held and control
the original data used for those domains, but you can't generalize that model
and IMHO it doesn't work if you try to push it down to libvirt or virsh,

  makes sense ?


Red Hat Virtualization group http://redhat.com/virtualization/
Daniel Veillard      | virtualization library  http://libvirt.org/
veillard at redhat.com  | libxml GNOME XML XSLT toolkit  http://xmlsoft.org/
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