[Openstack-operators] Two regions and so two metadata servers sharing the same VLAN
Gilles Mocellin
gilles.mocellin at nuagelibre.org
Thu Dec 3 23:56:10 UTC 2015
Hum, I don't think so. Things like hostname must be only known by the
neutron instance of one region...
Le 03/12/2015 00:01, Kevin Benton a écrit :
> Are both metadata servers able to provide metadata for all instances
> of both sides? If so, why not disable isolated metadata on one of the
> sides so only one of the DHCP agents will respond?
>
>
> On Thu, Nov 26, 2015 at 6:49 AM, <gilles.mocellin at nuagelibre.org
> <mailto:gilles.mocellin at nuagelibre.org>> wrote:
>
> Hello stackers !
>
> Sorry, I also cross-posted that question here
> https://ask.openstack.org/en/question/85195/two-regions-and-so-two-metadata-servers-sharing-the-same-vlan/
>
> But I think I can reach a wider audience here.
>
> So here's my problem.
>
> I'm facing an non-conventional situation. We're building a two
> region Cloud to separate a VMware backend and a KVM one. But both
> regions share the same 2 VLANs where we connect all our instances.
>
> We don't use routers, private network, floating IPs... I've
> enabled enable_isolated_metadata, so the metadata IP is inside the
> dhcp namespace and there's a static route in the created instances
> to it via the dhcp's IP. The two DHCPs could have been a problem
> but we will use separate IP ranges, and as Neutron sets static
> leases with the instances MAC address, they should not interfere.
>
> The question I've been asked is whether we will have network
> problems with the metadata server IP 169.254.169.254, that will
> exist in 2 namepaces on 2 neutron nodes but on the same VLAN. So
> they will send ARP packets with different MAC, and will perhaps
> perturb access to the metadata URL form the instances.
>
> Tcpdump shows nothing wrong, but I can't really test now because
> we haven't got yet the two regions. What do you think ?
>
> Of course, the question is not about why we choose to have two
> regions. I would have chosen Host Agregates to separate VMware and
> KVM, but cinder glance should have been configure the same way.
> And with VMware, it's not so feasible.
>
> Also, if we can, we will try to have separate networks for each
> regions, but it involves a lot of bureaucracy here...
>
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>
> --
> Kevin Benton
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