[ovirt-users] changing ip of host and its ovirtmgmt vlan

[Alona Kaplan]

On Wed, Sep 27, 2017 at 5:48 PM, Gianluca Cecchi <gianluca.cecchi at gmail.com>
wrote:

> On Wed, Sep 27, 2017 at 4:25 PM, Michael Burman <mburman at redhat.com>
> wrote:
>
>> Hello Gianluca,
>>
>> Not sure i fully understood, but, if the host's IP has changes and the
>> vlan then the correct flow will be:
>>
>> 1) Remove the host
>> 2) Edit the management network with vlan tag - the vlan you need/want
>> 3) Add/install the host - make sure you using the correct/new IP(if using
>> IP) or the correct FQDN(if has changed).
>>
>> Note that doing things manually on the host such as changing ovirtmgmt's
>> configuration without the engine or vdsm may cause problems and will not
>> persist the changes during reboots. If the host's IP has changed or it's
>> FQDN then you must install the host again.
>>
>> Cheers)
>>
>
> Original situation was:
>
> 1 DC
> 1 Cluster: CLA with 2 hosts: host1 and host2
> ovirtmgmt defined on vlan10
>
> engine is an external server on VLAN5 that can reach VLAN10 of hosts
> So far so good
>
> Need to add another host that is in another physical server room. Here
> VLAN10 is not present, so I cannot set ovirtmgmt
> If I understand correctly, the VLAN assigned to ovirtmgmt is a DC
> property: I cannot have different vlans assigned to ovirtmgmt in different
> clusters of the same DC, correct?
>
> So the path:
> Create a second cluster CLB and define on it the logical network
> ovirtmgmt2 on VLAN20 and set it as the mgmt network for that cluster
> Add the new host host3 to CLB.
>
> So far so good: the engine on VLAN5 is able to manage the hosts of CLA ad
> CLB with their mgmt networks in VLAN10 and VLAN20
>
> Now it is decided to create a new VLAN30 that is transportable across the
> the 2 physical locations and to have host1, host2, host3 to be part of a
> new CLC cluster where the mgmt network is now on VLAN30
>
> Can I simplify operations, as many VMs are already in place in CLA and CLB?
> So the question arises:
>
> the 3 hosts were added originally using their dns hostname and not their
> IP address.
> Can I change my dns settings so that the engine resolves the hostnames
> with the new IPs and change vlan of ovirtmgmt?
>

You can -
1. Move the host to maintenance mode.
2. Change the cluster of the hosts to the new one.
3. Running setupNetworks + save network configuration directly on the host
removing the old management network and configuring the new one (with new
vlan and ip).
 Petr, can you please provide the syntax of the command?

* You may first try doing this step via the ui. Make sure you uncheck
the 'Verify
connectivity between Host and Engine' checkbox in the Setup Networks window.
I'm not sure it will work, maybe the engine will block it since you're
trying to touch the nic with the management ip.

4. Change the dns setting to resolve to the new IPs.

>
> And if I decide to start from scratch with this new cluster CLC on VLAN30,
> can I retain my old 3 hostnames (resolving to their new IPs)? How?
>

You can -
1. remove the host from the original clusters
2. remove all the network from the host using Petr's vdsm tool (
https://gerrit.ovirt.org/#/c/79495/)
3. change the dns setting to resolve to the new IPs.
4. Add the host to the new cluster.


>
> Hope I was able to clarify a bit the scenario
>
> Gianluca
>
>
>
>
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