[Fedora-xen] Xen Documentation

[Daniel P. Berrange]

On Fri, May 30, 2008 at 03:18:57PM +0100, Ian Jackson wrote:
> Daniel P. Berrange writes ("Re: [Fedora-xen] Xen Documentation"):
> > On Fri, May 30, 2008 at 02:51:18PM +0100, Ian Jackson wrote:
> > > Open Source Xen doesn't store configuration details in a database.  It
> > > uses plain text configuration files in /etc.  To a limited amount
> > > information about xend-managed domains is stored in /var in what is
> > > arguably a kind of database, but not in xenstore.
> > 
> > Or it uses text files in /var/lib/xen for domain configs.
> 
> Right, that's what I meant.
> 
> > > I don't know what, if anything, is changing in Fedora.  It's difficult
> > > to tell from that blog posting.  Perhaps some of the Fedora guys here
> > > on this list can enlighten us; otherwise ask on fedora-xen ?
> > 
> > We haven't changed anything in Xen in this regard. In Xen 3.0.3 and
> > ealier the only place to store config files was in /etc, and XenD had
> > no concept of inactive domains. In Xen 3.0.4 or later, XenD can directly
> > manage inactive domains, storing their configs in /var/lib/xen/. IF
> > libvirt detects a new enough XenD it will use its inactive domain
> > management capabilities instead of putting configs in /etc, since this
> > gives access to a greater level of functionality.
> 
> That sounds sensible.  I'm not sure how that relates to the blog
> posting mentioned by the original poster.

That posting is mostly based on a mis-understanding of what XenD is doing,
but also the fact that there is no way to get the config back out of XenD
using 'xm'. ie, you can load a traditional /etc/xen style config into XenD
using 'xm new CONFIG', but you can't ask XenD to generate you a traditional
style cofnig for one of the VMs its managing. Not an issue if you're using
libvirt for management, since it doesn't use /etc/xen style configs anyway.
While, there are a few people who need to use /etc/xen configs to get access
to specific features not supported in libvirt (PCI device passthrough), they
are a small niche.  On the whole switching to using the new inactive domain
management APIs in XenD was a net-win, with the benefits far outweighing
the disadvantages.

Dan.
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