Open Stack

Dual-room link:

[1] IBM and Cisco: Together for a World Class Data Center, Page 141.
http://books.google.fr/books?id=DHjJAgAAQBAJ&pg=PA141#v=onepage&q&f=false


> -----Message d'origine-----
> De : Khanh-Toan Tran [mailto:khanh-toan.tran at cloudwatt.com]
> Envoyé : jeudi 3 avril 2014 17:22
> À : OpenStack Development Mailing List (not for usage questions)
> Objet : RE: [openstack-dev] [Nova] Hosts within two Availability Zones :
possible
> or not ?
>
> +1 for AZs not sharing hosts.
>
> Because it’s the only mechanism that allows us to segment the
datacenter.
> Otherwise we cannot provide redundancy to client except using Region
which is
> dedicated infrastructure and networked separated and anti-affinity
filter which
> IMO is not pragmatic as it has tendency of abusive usage.  Why
sacrificing this
> power so that users can select the types of his desired physical hosts ?
The latter
> can be exposed using flavor metadata, which is a lot safer and more
controllable
> than using AZs. If someone insists that we really need to let users
choose the
> types of physical hosts, then I suggest creating a new hint, and use
aggregates
> with it. Don’t sacrifice AZ exclusivity!
>
> Btw, there is a datacenter design called “dual-room” [1] which I think
best fit for
> AZs to make your cloud redundant even with one datacenter.
>
> Best regards,
>
> Toan
>
> > -----Message d'origine-----
> > De : Chris Friesen [mailto:chris.friesen at windriver.com]
> > Envoyé : jeudi 3 avril 2014 16:51
> > À : openstack-dev at lists.openstack.org
> > Objet : Re: [openstack-dev] [Nova] Hosts within two Availability Zones
> > : possible or not ?
> >
> > On 04/03/2014 07:51 AM, Sylvain Bauza wrote:
> > > Hi,
> > >
> > > I'm currently trying to reproduce [1]. This bug requires to have the
> > > same host on two different aggregates, each one having an AZ.
> > >
> > > IIRC, Nova API prevents hosts of being part of two distinct AZs [2],
> > > so IMHO this request should not be possible.
> > > That said, there are two flaws where I can identify that no
> > > validation is done :
> > >   - when specifying an AZ in nova.conf, the host is overriding the
> > > existing AZ by its own
> > >   - when adding an host to an aggregate without AZ defined, and
> > > afterwards update the aggregate to add an AZ
> > >
> > >
> > > So, I need direction. Either we consider it is not possible to share
> > > 2 AZs for the same host and then we need to fix the two above
> > > scenarios, or we say it's nice to have 2 AZs for the same host and
> > > then we both remove the validation check in the API and we fix the
> > > output issue reported in the original bug [1].
> >
> > Currently host aggregates are quite general, but the only ways for an
> > end-user to make use of them are:
> >
> > 1) By making the host aggregate an availability zones (where each host
> > is only supposed to be in one availability zone) and selecting it at
> > instance creation time.
> >
> > 2) By booting the instance using a flavor with appropriate metadata
> > (which can only be set up by admin).
> >
> >
> > I would like to see more flexibility available to the end-user, so I
> > think we should either:
> >
> > A) Allow hosts to be part of more than one availability zone (and
> > allow selection of multiple availability zones when booting an
> > instance), or
> >
> > B) Allow the instance boot scheduler hints to interact with the host
> > aggregate metadata.
> >
> > Chris
> >
> >
> > _______________________________________________
> > OpenStack-dev mailing list
> > OpenStack-dev at lists.openstack.org
> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev