[Fedora-xen] Xen Documentation

[Daniel P. Berrange]

On Thu, May 29, 2008 at 08:06:32PM -0400, Gast?n Keller wrote:
> On Thu, May 29, 2008 at 7:53 PM, Emre ERENOGLU <erenoglu at gmail.com> wrote:
> > Hi Gaston,
> >
> > It's true that some documentation is outdated. However, for the "/etc/xen"
> > isssue, my custom Xen 3.2 setup still stores ( and I do store there also) my
> > config files there.
> >
> > Maybe what you're saying is "Fedora Specific" which I could understand as
> > it's fedora mailing list.
> 
> _The Fedora team has followed the Xensource model and begun to store
> all VM configuration details in a database, referred to as xenstore._

No, xenstore only holds information about active VMs. The persistent VM config
is managed by XenD itself, and stored in files under /var/lib/xend.

> Source: http://enterpriselinuxlog.blogs.techtarget.com/2007/06/07/fedora-7-xen-first-look/
> 
> Then, you might be right. I interpreted it was a modification from
> Xen, not from Fedora (previously introduced by Xensource).

This was all implemented by upstream Xen. Libvirt probes for this capability
in XenD and if it finds it, it will make use of it, since libvirt wants to
be able to manage inactive VMs too. Since Fedora 7 was the first to ship
this capability in Xen, it was the first release where libvirt would enable
this inactive domain management.
 
> So, what is the advantage behind this movement?

The key reason for this was to allow XenD the ability to manage inactive
domains. So all its APIs for modifying VM configs now work for running
and inactive VMs. This is impossible for XenD if using /etc/xen. This is
why 'xm list' won't show you configs stored in /etc/xen.

Dan.
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