[Ovirt-devel] Updating oVirt Server to the latest Matahari 0.4.0 schema

Sun Nov 14 12:46:10 UTC 2010

Thanks for the heads-up. A few remarks/questions :
1. we should keep the augeas system for assigning network interfaces because
it's the only way to reliably map the correct interfaces to the correct
databases entries. Besides there is now support for vlan interfaces creation
thru augeas, which is not supported in matahari, I assume. matahari returns
all the vlan-tagged interfaces as if there were real interfaces and we have
to filter them in host-register
2. in april there was a series of commits switching ovirt-server from
ruby-qpid to ruby-qmf rpm. Those are two implementations of ruby bindings to
qmf. (see http://mo.morsi.org/blog/node/288 for more details). I have found
ruby-qmf to be unstable and buggy so I reverted to ruby-qpid in my local
branch. I would like to know what is the plan in QPID regarding the ruby
bindings. Is ruby-qpid ditched in profit of ruby-qmf, or the 2 are going to
cohabit forever ? Because I'd really like to push the revert to ovirt-server
next. When this is clarified, we can take care of migrating to new matahari.
3.what version of matahari is in RHEL 6 ? what version will be in fedora 14
? wouldn't it be good to maintain an ovirt version for rhel/centos 6 ?

On Fri, Nov 12, 2010 at 2:24 PM, Alan Pevec <apevec at redhat.com> wrote:

> Hi all,
>
> I looked at patching oVirt Server to work with the latest Matahari schema,
> from Matahari's 'next' branch, version 0.4.0.
> ovirt-server depends on matahari version 0.0.5, which is currently latest
> in Fedora, and it is used during Node registration, to enumerate hardware
> information.
> Usage extracted from src/host-browser/host-register.rb is as follows:
>
> host_list = @qmfc.objects(:package => 'com.redhat.matahari.host', :class =>
> 'Host')
> host properties used:
>        object_id
>        object_id.agent_key
>        uuid
>        hostname
>        hypervisor
>        arch
>        memory
>
> This is all good, those properties do exist in new Matahari 0.4.0 schema,
> patch for this part would be simply:
> --- a/src/host-browser/host-register.rb
> +++ b/src/host-browser/host-register.rb
> @@ -143,7 +143,7 @@ class HostRegister < Qmf::ConsoleHandler
>         debugputs "Agent #{agent.key}.connected!"
>         agent_connected(agent)
>  -        host_list = @qmfc.objects(:package => 'com.redhat.matahari',
> :class => 'host')
> +        host_list = @qmfc.objects(:package => 'com.redhat.matahari.host',
> :class => 'Host')
>        puts "host_list length is #{host_list.length}"
>         host_list.each do |host|
>             if host.object_id.agent_key == agent.key
>
>
> Next, old Matahari has 1:N relationship between host and cpu objects,
> ovirt-server uses it by retrieving a list of cpus for each host:
>
> cpu_info = @qmfc.objects(:package => 'com.redhat.matahari', :class =>
> 'cpu', 'host' => host.object_id)
> cpu properties used:
>        cpunum
>        corenum
>        numcores
>        vendor
>        model
>        family
>        cpuid_lvl
>        speed
>        cache
>        flags[0..251]
>
> New Matahari changed the model, here are CPU-related properties from 0.4.0
> Host object, there isn't separate cpu class anymore:
>    processors        uint8               ReadOnly          The number of
> physical CPUs.
>    cores             uint8               ReadOnly          The total number
> of processor cores.
>    model             long-string         ReadOnly          The processor(s)
> model description.
>
> "model" is descriptive string, so it's not good enough to replace old CPU
> details.
> On the other hand, oVirt does not really use all those CPU properties, they
> are just copied into ovirt database.
> CPU information could be used to check migration compatibility, but this
> should be done through libvirt/libvirt-qpid anyway.
> So I would propose ovirt-server to just remove cpus table, what does
> ovirt-devel say?
>
>
> Last are network interfaces, also 1:N relationship:
> nic_info = @qmfc.objects(:package => 'com.redhat.matahari', :class =>
> 'nic', 'host' => host.object_id)
> nic properties used:
>        macaddr
>        interface
>                seems to be bug in host-register.rb, it uses
> "interface_name" property which doesn't exist in matahari 0.0.5 QMF schema!
>        bandwidth
>
> "nic" class is gone, there's new class 'com.redhat.matahari.net:network'
> with "hostname" property only and following methods:
> 'status' Check a network interface
> 'stop' Stop a network interface
> 'start' Start a network interface
> 'destroy' Remove network interface
> 'list' List IP addresses
> 'describe' Obtain XML description of a network interface status
>
> Matahari now basically wraps netcf calls in its network agent, so
> properties like MAC are not directly available, it can be extracted from
> netcf XML, output of the 'describe' method.
>
> But there's more to it since, netcf can also configure interfaces (not yet
> in Matahari schema, but it is planned).
> Currently, ovirt-server provides network configuration which is downloaded
> by the Node on boot and applied (via augeas).
> Question is should ovirt-server switch fully to netcf (via Matahari)?
> I'm not sure how does netcf handle unstable interface names, seems that it
> relies on them being stable which is not the case in the stateless
> environment like oVirt Node.
>
> Alan
>
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