[openstack-dev] About multihost patch review

Yongsheng Gong gongysh at unitedstack.com
Fri Aug 30 02:00:14 UTC 2013


On Thu, Aug 29, 2013 at 1:28 AM, Vishvananda Ishaya
<vishvananda at gmail.com>wrote:

>
> On Aug 26, 2013, at 6:14 PM, Maru Newby <marun at redhat.com> wrote:
>
> >
> > On Aug 26, 2013, at 4:06 PM, Edgar Magana <emagana at plumgrid.com> wrote:
> >
> >> Hi Developers,
> >>
> >> Let me explain my point of view on this topic and please share your
> thoughts in order to merge this new feature ASAP.
> >>
> >> My understanding is that multi-host is nova-network HA  and we are
> implementing this bp
> https://blueprints.launchpad.net/neutron/+spec/quantum-multihost for the
> same reason.
> >> So, If in neutron configuration admin enables multi-host:
> >> etc/dhcp_agent.ini
> >>
> >> # Support multi host networks
> >> # enable_multihost = False
> >>
> >> Why do tenants needs to be aware of this? They should just create
> networks in the way they normally do and not by adding the "multihost"
> extension.
> >
> > I was pretty confused until I looked at the nova-network HA doc [1].
>  The proposed design would seem to emulate nova-network's multi-host HA
> option, where it was necessary to both run nova-network on every compute
> node and create a network explicitly as multi-host.  I'm not sure why
> nova-network was implemented in this way, since it would appear that
> multi-host is basically all-or-nothing.  Once nova-network services are
> running on every compute node, what does it mean to create a network that
> is not multi-host?
>
> Just to add a little background to the nova-network multi-host: The fact
> that the multi_host flag is stored per-network as opposed to a
> configuration was an implementation detail. While in theory this would
> support configurations where some networks are multi_host and other ones
> are not, I am not aware of any deployments where both are used together.
>
> That said, If there is potential value in offering both, it seems like it
> should be under the control of the deployer not the user. In other words
> the deployer should be able to set the default network type and enforce
> whether setting the type is exposed to the user at all.
>
yes, the default is not multihost, admin (by policy) can set up multihost
network

>
> Also, one final point. In my mind, multi-host is strictly better than
> single host, if I were to redesign nova-network today, I would get rid of
> the single host mode completely.
>
> problem is: the current design of neutron is single host already (If I get
your point). To do multihost automatically, it needs much effort .

> Vish
>
> >
> > So, to Edgar's question - is there a reason other than 'be like
> nova-network' for requiring neutron multi-host to be configured per-network?
> >
> >
> > m.
> >
> > 1:
> http://docs.openstack.org/trunk/openstack-compute/admin/content/existing-ha-networking-options.html
> >
> >
> >> I could be totally wrong and crazy, so please provide some feedback.
> >>
> >> Thanks,
> >>
> >> Edgar
> >>
> >>
> >> From: Yongsheng Gong <gongysh at unitedstack.com>
> >> Date: Monday, August 26, 2013 2:58 PM
> >> To: "Kyle Mestery (kmestery)" <kmestery at cisco.com>, Aaron Rosen <
> arosen at nicira.com>, Armando Migliaccio <amigliaccio at vmware.com>, Akihiro
> MOTOKI <amotoki at gmail.com>, Edgar Magana <emagana at plumgrid.com>, Maru
> Newby <marun at redhat.com>, Nachi Ueno <nachi at nttmcl.com>, Salvatore
> Orlando <sorlando at nicira.com>, Sumit Naiksatam <
> sumit.naiksatam at bigswitch.com>, Mark McClain <mark.mcclain at dreamhost.com>,
> Gary Kotton <gkotton at vmware.com>, Robert Kukura <rkukura at redhat.com>
> >> Cc: OpenStack List <openstack-dev at lists.openstack.org>
> >> Subject: Re: About multihost patch review
> >>
> >> Hi,
> >> Edgar Magana has commented to say:
> >> 'This is the part that for me is confusing and I will need some
> clarification from the community. Do we expect to have the multi-host
> feature as an extension or something that will natural work as long as the
> deployment include more than one Network Node. In my opinion, Neutron
> deployments with more than one Network Node by default should call DHCP
> agents in all those nodes without the need to use an extension. If the
> community has decided to do this by extensions, then I am fine' at
> >>
> https://review.openstack.org/#/c/37919/11/neutron/extensions/multihostnetwork.py
> >>
> >> I have commented back, what is your opinion about it?
> >>
> >> Regards,
> >> Yong Sheng Gong
> >>
> >>
> >> On Fri, Aug 16, 2013 at 9:28 PM, Kyle Mestery (kmestery) <
> kmestery at cisco.com> wrote:
> >>> Hi Yong:
> >>>
> >>> I'll review this and try it out today.
> >>>
> >>> Thanks,
> >>> Kyle
> >>>
> >>> On Aug 15, 2013, at 10:01 PM, Yongsheng Gong <gongysh at unitedstack.com>
> wrote:
> >>>
> >>>> The multihost patch is there for a long long time, can someone help
> to review?
> >>>> https://review.openstack.org/#/c/37919/
> >>>
> >>
> >
> >
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>
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