7:48 p.m.
In my setup the reason why I attempted to use OVS/OVN is that I
(currently) have two hosts in a data center (Hetzner) which does not
have a common subnet. Each of these hosts have one public IPv4 address.
Because of that I want the ovirt networks to be on private ip ranges and
they do not correspond to any physical network interfaces. I've been
able to work around that by making dummy interfaces visible for vdsm to
which it can bind the ovirtmgmt bridge.
It also means that I need to connect the obirtmgmt bridges on the two
hosts with tunnels. With OVS I can set that up manually and it works
great, issue is that vdsm wants to control the network interfaces and
creates an OVS bridge with random name to attach ovirtmgmt port to,
hence I have no convenient way to connect these bridges. I could put a
hook in after_network_setup to create tunnels, but I suppose the OVS
bridges needs to have the same name on both sides.
I want to use ovirt for a test environment with quite complex network,
hence why OVN is desired to be able to set it up virtual.
With OVN + physnet as you describe it I assume I should get the desired
functionality as ovirtmgmt needs to be present on all hosts. Since you
disabled changing switch type in engine gui I changed it in db, don't
know if anything more is needed, and in the vdsm persistent file. On
vdsm level that works fine, the OVS bridge with random name is created
with ovirtmgmt port, but as you write since 4.2.3 it no longer creates
the port for hosted engine on the OVS bridge. I worked around that with
a hook script that add the missing elements to interface section of the
vm xml.
My understanding is that for OVN+physnet then OVS switch is needed but
doesn't then the ovirtmgmt port has to be on an OVS bridge? If so then
hosted engine must be able to connect it's port to the same bridge.
Next concern is where should the OVN databases be? With hosted-engine
setup they are created on the vm which seems like a chicken and the egg
issue to me as how could the hosts where ovn-controller runs be able to
connect to db before the vm has started? In my setup the vm only have
private address which means the other host is not able to reach ovn
database until the virtual network has established.
Therefore I created OVN databases on one of the hosts, and configured
with ssl cert/keys so that they are able to communicate fine. I
configured ovirt-provider-ovn running on hosted engine vm to connect to
the db host but even when ovn-remote is set to the correct address on
the host the requests from ovirt-provider-ovn towards port 6641 still
goes to the engine vm.
Are there any additional steps that is needed to take?
/Sverker
Den 2018-05-25 kl. 17:41, skrev Dan Kenigsberg:
I believe the user community deserves a little background for this
decision. OVS has been "experimental" since ovirt-4.0.z with migration
disabled by default. We were not aware of huge benefits it had
over the default Linux bridge, and did not expect people to be using
it in important deployments.
I would love to hear your experience regarding our OVS support, and
why you have chosen it.
In ovirt-4.2.0, the way in which VM libvirt definition is built has
changed considerably, and takes place in ovirt-engine, not in vdsm.
The vdsm code that supports OVS connectivity was disabled in
ovirt-4.2.3 which means that indeed, the experimental OVS feature is
no longer available for direct usage (unless you still use cluster
compatibility level 4.1)
However, as Thomas Davis explains, with OVN + physnet, ovirt-4.2 gives
you a matching functionality, including live migration out-of-the-box.
OVS switchtype was upgraded from "experimental" to "tech-preview".
I'd
like to drop the advisory altogether, but we keep it because we still
have bugs and
missing features comparing to Linux bridge clusters.
We've blocked changing the switchtype of existing clusters because
this functionality is buggy (particularly on the SPM host), and as of
ovirt-4.2, we do not have code to support live migration from a Linux
bridge host to an OVS one. Only cold migration is possible. We kept it
open over REST to allow testing and bugfixes to that flow, as well as
usage by careful users.
Thanks for using oVirt and its new features, and for engaging with the
community.
Regards,
Dan.
On Tue, May 22, 2018 at 9:20 PM, <tadavis(a)lbl.gov> wrote:
> The answer is..
>
> OVN replaced OVS as the networking technology. You cannot switch back to legacy,
they disabled switching between ovs and legacy in the default (1st) datacenter using the
gui. You can however, use Ansible to switch it.
>
> Remove the VDSM ovs setting, it will just mess you up, and it's not supported in
4.2
>
> To able to migrate a VM in 4.2, you have use OVN with OVS.
>
> I did this a few months back, on a 4.2.2 hosted-engine setup:
>
> 0) To setup a node in a cluster, make sure the cluster is in OVS, not
> legacy.
>
> 1) Make sure you have an OVN controller setup somewhere. Default
> appears to be the ovirt-hosted-engine.
> a) you should also have the external network provider for OVN
> configured also; see the web interface.
>
> 2) when you install the node, make sure it has openvswitch installed and
> running - ie:
> a) 'systemctl status openvswitch' says it's up and running. (be
sure
> it's enable also)
> b) 'ovs-vsctl show' has vdsm bridges listed, and possibly a br-int
> bridge.
>
> 3) if there is no br-int bridge, do 'vdsm-tool ovn-config
> ovn-controller-ip host-ip'
>
> 4) when you have configured several nodes in the OVN, you should see
> them listed as geneve devices in 'ovs-vsctl show', ie:
>
> This is a 4 node cluster, so the other 3 nodes are expected:
>
> [ root at d8-r12-c1-n3 ~]# ovs-vsctl show
> 42df28ba-ffd6-4e61-b7b2-219576da51ab
> Bridge br-int
> fail_mode: secure
> Port "ovn-27461b-0"
> Interface "ovn-27461b-0"
> type: geneve
> options: {csum="true", key=flow,
remote_ip="192.168.85.91"}
> Port "vnet1"
> Interface "vnet1"
> Port "ovn-a1c08f-0"
> Interface "ovn-a1c08f-0"
> type: geneve
> options: {csum="true", key=flow,
remote_ip="192.168.85.87"}
> Port "patch-br-int-to-f7a19c7d-021a-455d-bf3a-c15e212d8831"
> Interface
> "patch-br-int-to-f7a19c7d-021a-455d-bf3a-c15e212d8831"
> type: patch
> options:
> {peer="patch-f7a19c7d-021a-455d-bf3a-c15e212d8831-to-br-int"}
> Port "vnet0"
> Interface "vnet0"
> Port "patch-br-int-to-7874ba85-8f6f-4e43-9535-5a1b1353a9ec"
> Interface
> "patch-br-int-to-7874ba85-8f6f-4e43-9535-5a1b1353a9ec"
> type: patch
> options:
> {peer="patch-7874ba85-8f6f-4e43-9535-5a1b1353a9ec-to-br-int"}
> Port "ovn-8da92c-0"
> Interface "ovn-8da92c-0"
> type: geneve
> options: {csum="true", key=flow,
remote_ip="192.168.85.95"}
> Port br-int
> Interface br-int
> type: internal
> Bridge "vdsmbr_LZmj3uJ1"
> Port "vdsmbr_LZmj3uJ1"
> Interface "vdsmbr_LZmj3uJ1"
> type: internal
> Port "net211"
> tag: 211
> Interface "net211"
> type: internal
> Port "eno2"
> Interface "eno2"
> Bridge "vdsmbr_e7rcnufp"
> Port "vdsmbr_e7rcnufp"
> Interface "vdsmbr_e7rcnufp"
> type: internal
> Port ipmi
> tag: 20
> Interface ipmi
> type: internal
> Port ovirtmgmt
> tag: 50
> Interface ovirtmgmt
> type: internal
> Port "patch-f7a19c7d-021a-455d-bf3a-c15e212d8831-to-br-int"
> Interface
> "patch-f7a19c7d-021a-455d-bf3a-c15e212d8831-to-br-int"
> type: patch
> options:
> {peer="patch-br-int-to-f7a19c7d-021a-455d-bf3a-c15e212d8831"}
> Port "eno1"
> Interface "eno1"
> Port "patch-7874ba85-8f6f-4e43-9535-5a1b1353a9ec-to-br-int"
> Interface
> "patch-7874ba85-8f6f-4e43-9535-5a1b1353a9ec-to-br-int"
> type: patch
> options:
> {peer="patch-br-int-to-7874ba85-8f6f-4e43-9535-5a1b1353a9ec"}
> ovs_version: "2.7.3"
>
> 5) Create in the cluster the legacy style bridge networks - ie,
> ovirtmgmt, etc. Do this just like you where creating them for the
> legacy network. Define the VLAN #, the MTU, etc.
>
> 6) Now, create in the network config, the OVN networks - ie,
> ovn-ovirtmgmt is on an external provider (select OVN), and make sure
> 'connect to physical network' is checked, and the correct network from
> step 5 is picked. Save this off.
>
> This will connect the two networks together in a bridge, and all
> services are visible to both ie dhcp, dns..
>
> 7) when you create the VM, select the OVN network interface, not the
> legacy bridge interface (this is why I decided to prefix with 'ovn-').
>
> 8) Create the vm, start it, migrate, stop, re-start, etc, it all should
> work now.
>
> Lots of reading.. lots of interesting stuff found.. finally figured
> this out after reading a bunch of bug fixes for the latest RC (released
> today)
>
> The only doc link:
>
>
https://ovirt.org/develop/release-management/features/network/provider-ph...
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