[Ovirt-devel] Re: Ovirt-qpid API

[Daniel P. Berrange]

On Wed, Oct 22, 2008 at 08:32:58PM +0200, Chris Lalancette wrote:
> Ian Main wrote:
> > OK, here's another go around at this.  This has all the bells and whistles
> > for network config.  Please take a moment to go through it and make sure I've
> > done this properly.
> > 
> > BTW, the UUID from hal is in there so that we can map this host to the host
> > in libvirt.  Hopefully they will always be the same.  Xen doesn't mess with
> > this does it in dom0?
> 
> No, but it's completely unreliable in general.  Don't rely on it for anything.

There are really two UUIDs you need to consider

 - the hardware identity
 - the operating system identity.

The hardware identity is the UUID. For real hardware, the it is usually,
but not always, unique / usable. For virtual hardware it should be 
guarenteed unique unless the virt mgmt app screws up.

We do need to include the UUID from hal in the info because ultimately
you could be running the qpid agent in the guest for nested virt and
want to correlate host & guest views of the world. 

The operating system identity is the security token (ie kerberos principle,
or x509 cert) is what is guarenteed to provide a unique identity for an OS
instance.

So the OS identity is the key piece of info. The oVirt node bootstrap 
process will take care of assigning identity. The hardware identity is 
really only useful for asset tracking / inventory metadata, and to 
provide a heuristic for data correlation, if you don't have access to 
the true OS identity at that point.


Daniel
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