----- Original Message -----
> From: "Mark Wu" <wu...@linux.vnet.ibm.com>
> To: "VDSM Project Development" <vdsm-devel@lists.fedorahosted.org>
> Cc: "Alon Bar-Lev" <alo...@redhat.com>, "Dan Kenigsberg" <dan...@redhat.com>, 
> "Simon Grinberg" <si...@redhat.com>,
> "Antoni Segura Puimedon" <asegu...@redhat.com>, "Igor Lvovsky" 
> <ilvov...@redhat.com>, "Daniel P. Berrange"
> <berra...@redhat.com>
> Sent: Monday, December 3, 2012 7:39:49 AM
> Subject: Re: [vdsm] Back to future of vdsm network configuration
> 
> On 11/29/2012 04:24 AM, Alon Bar-Lev wrote:
> >
> > ----- Original Message -----
> >> From: "Dan Kenigsberg" <dan...@redhat.com>
> >> To: "Alon Bar-Lev" <alo...@redhat.com>
> >> Cc: "Simon Grinberg" <si...@redhat.com>, "VDSM Project
> >> Development" <vdsm-devel@lists.fedorahosted.org>
> >> Sent: Wednesday, November 28, 2012 10:20:11 PM
> >> Subject: Re: [vdsm] MTU setting according to ifcfg files.
> >>
> >> On Wed, Nov 28, 2012 at 12:49:10PM -0500, Alon Bar-Lev wrote:
> >>> Itamar though a bomb that we should co-exist on generic host,
> >>> this
> >>> is
> >>> something I do not know to compute. I still waiting for a
> >>> response
> >>> of
> >>> where this requirement came from and if that mandatory.
> >>>
> >> This bomb has been ticking since ever. We have ovirt-node images
> >> for
> >> pure hypervisor nodes, but we support plain Linux nodes, where
> >> local
> >> admins are free to `yum upgrade` in the least convenient moment.
> >> The
> >> latter mode can be the stuff that nightmares are made of, but it
> >> also
> >> allows the flexibility and bleeding-endgeness we all cherish.
> >>
> > There is a different between having generic OS and having generic
> > setup, running your email server, file server and LDAP on a node
> > that running VMs.
> >
> > I have no problem in having generic OS (opposed of ovirt-node) but
> > have full control over that.
> >
> > Alon.
> Can I say we have got agreement on oVirt should cover two kinds of
> hypervisors?  Stateless slave is good for pure and normal
> virtualization
> workload, while generic host can keep the flexibility of
> customization.
> In my opinion, it's good for the oVirt community to provide choices
> for
> users.  They could customize it in production, building and even
> source
> code according to their requirements and skills.

I also think it will be good to support both modes! It will also good if we can 
rule the world! :)

Now seriously... :)

If we want to ever have a working solution we need to focus, dropping wishful 
requirements in favour of the minimum required that will allow us to reach to 
stable milestone.

Having a good clean interface for vdsm network within the stateless mode, will 
allow a persistent implementation to exists even if the whole implementation of 
master and vdsm assume stateless. This kind of implementation will get a new 
state from master, compare to whatever exists on the host and sync.

I, of course, will be against investing resources in such network management 
plugin approach... but it is doable, and my vote is not something that you 
cannot safely ignore.

Having said that, let's come back to your original claim:
"""while generic host can keep the flexibility of customization."""

NOBODY, and I repeat my answer to Dan, NOBODY claim we should not support 
generic host.
But the term 'generic' seems to confuse everyone... generic is a a host does 
not mean administrator can do whatever he likes, it just a host that is 
installed using standard distribution installation procedure.

Using 'generic host' can be done with either stateful or stateless modes.

However what and how customization can be done to a resource that is managed by 
VDSM (eg: storage, network) is a complete different question.

There cannot be two managers to the same resource, it is a rule of thumb, any 
other approach is non-deterministic and may lead to huge resource investment 
with almost no benefit, as it will never be stable.

> So moving back to
> the
> discussion network configuration,  I would like to suggest we could
> adopt both of the two solutions.
> 
> dynamic way (as Alon suggested in his previous mail.) -- for oVirt
> node.
> It will take a step towards real stateless. Actually it's also
> helpful
> to offload the transaction management from vdsm for the static way.

It will also provide the framework needed in order to provide network on demand 
as Livnat plan.
Define network resources (and I guess storage) when VM is moved to the host.
In this mode there is no other way to go!

> We're going to build vdsm network setup module on top of generic host
> network manager, like libvirt virInterface. But to persist the
> network
> configuration on oVirt node,  vdsm has to care about the details of
> lower level. If we only run the static way on the generic host, then
> host network manager could perform the rollback stuff on behalf of
> vdsm.  I only have two comments on dynamic way:
> 1. Do we really need to care about the management interface? How
> about
> just leaving it to installation and disallow to configure it at
> runtime.
> 2. How about putting the retrievement network configuration from
> engine
> into vdsm-reg?

vdsm-reg is going to be killed soon, just like the vdsm-bootstrap.
I was tempted to do this for 3.2, but I was taken...

> 
> static way -- for generic host. We didn't follow much on this topic
> in
> the thread.  So I would like to talk about my understanding to
> continue
> this discussion.
> As Dan said in the first message of this thread, openvswitch couldn't
> keep 3rd level configurations, so it's not appropriate to use itself
> to
> cover the base network configurations. Then we have two choices:
> netcf
> and NetworkManager. It seems netcf is not used as widely as NM.
> Currently, it supports fedora/rhel, debian/ubuntu and suse. To
> support a
> new distribution, you need add a converter to translate the
> interface's
> XML definition into native configuration, because netcf just covers
> the
> part of static configuration, and relies on the system network
> service
> to make configurations take effect.  Compared with netcf, it's easier
> to
> support new distribution because it has its own daemon to parse the
> self-defining key-value file and call netlink library to perform the
> live change. Besides that, NM can also monitor the physical
> interface's
> link status, and has the ability run callback on some events. Daniel
> mentioned that libvirt would support NM by the virInterface API.
> That's
> good for vdsm. But I found it didn't fit vdsm's requirements very
> well.
> 1. It doesn't allow to define a bridge on top of an existing
> interface.
> That means the schema requires you define the bridge port interface
> together with the bridge.
>     The vdsm setupNetwork verb allows creating a bridge with a given
> name of existing bonding. To work around it, vdsm has to get the
> bonding
> definition from libvirt or collect   information from /sys. And then
> put
> the bonding definition into bridge's definition.
> 2. It also removes its port interface, like bonding device together
> when
> remove bridge.  It's not expected by vdsm when the option
> 'implicitBonding' is unset. To work around it, vdsm has to re-create
> the
> bonding as said in 1.
> 3. mtu setting is propagated to nic or bond when setting a mtu to
> bridge. It could break mtu support in oVirt when adding a bridge with
> smaller mtu to a vlan whose slave nic is
>     also used by a bigger mtu network.
> 4. Some less used options are not allowed by the the schema, like
> some
> bonding modes and options.
> 
> Some of them could change in the backend NM.  But it's better to
> claim
> vdsm's requirements while libvirt is moving to NM. Is it better that
> if
> libvirt allow vdsm manipulate
> sub-element of a network?  Probably Igor and Antoni have more
> comments
> on it.

I don't like using libvirt for networking. We should interact directly with the 
host network manager or whatever alternative we choose.

Alon
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