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Hi Toan,
Is what you say related to :
https://blueprints.launchpad.net/nova/+spec/schedule-set-availability-zones?


2014-03-27 10:37 GMT+01:00 Khanh-Toan Tran <khanh-toan.tran at cloudwatt.com>:

>
>
> ----- Original Message -----
> > From: "Sangeeta Singh" <singhs at yahoo-inc.com>
> > To: "OpenStack Development Mailing List (not for usage questions)" <
> openstack-dev at lists.openstack.org>
> > Sent: Wednesday, March 26, 2014 6:54:18 PM
> > Subject: Re: [openstack-dev] [nova][scheduler] Availability Zones and
> Host aggregates..
> >
> >
> >
> > On 3/26/14, 10:17 AM, "Khanh-Toan Tran" <khanh-toan.tran at cloudwatt.com>
> > wrote:
> >
> > >
> > >
> > >----- Original Message -----
> > >> From: "Sangeeta Singh" <singhs at yahoo-inc.com>
> > >> To: "OpenStack Development Mailing List (not for usage questions)"
> > >><openstack-dev at lists.openstack.org>
> > >> Sent: Tuesday, March 25, 2014 9:50:00 PM
> > >> Subject: [openstack-dev] [nova][scheduler] Availability Zones and Host
> > >>aggregates..
> > >>
> > >> Hi,
> > >>
> > >> The availability Zones filter states that theoretically a compute node
> > >>can be
> > >> part of multiple availability zones. I have a requirement where I need
> > >>to
> > >> make a compute node part to 2 AZ. When I try to create a host
> aggregates
> > >> with AZ I can not add the node in two host aggregates that have AZ
> > >>defined.
> > >> However if I create a host aggregate without associating an AZ then I
> > >>can
> > >> add the compute nodes to it. After doing that I can update the
> > >> host-aggregate an associate an AZ. This looks like a bug.
> > >>
> > >> I can see the compute node to be listed in the 2 AZ with the
> > >> availability-zone-list command.
> > >>
> > >
> > >Yes it appears a bug to me (apparently the AZ metadata indertion is
> > >considered as a normal metadata so no check is done), and so does the
> > >message in the AvailabilityZoneFilter. I don't know why you need a
> > >compute node that belongs to 2 different availability-zones. Maybe I'm
> > >wrong but for me it's logical that availability-zones do not share the
> > >same compute nodes. The "availability-zones" have the role of partition
> > >your compute nodes into "zones" that are physically separated (in large
> > >term it would require separation of physical servers, networking
> > >equipments, power sources, etc). So that when user deploys 2 VMs in 2
> > >different zones, he knows that these VMs do not fall into a same host
> and
> > >if some zone falls, the others continue working, thus the client will
> not
> > >lose all of his VMs. It's smaller than Regions which ensure total
> > >separation at the cost of low-layer connectivity and central management
> > >(e.g. scheduling per region).
> > >
> > >See: http://www.linuxjournal.com/content/introduction-openstack
> > >
> > >The former purpose of regouping hosts with the same characteristics is
> > >ensured by host-aggregates.
> > >
> > >> The problem that I have is that I can still not boot a VM on the
> > >>compute node
> > >> when I do not specify the AZ in the command though I have set the
> > >>default
> > >> availability zone and the default schedule zone in nova.conf.
> > >>
> > >> I get the error ³ERROR: The requested availability zone is not
> > >>available²
> > >>
> > >> What I am  trying to achieve is have two AZ that the user can select
> > >>during
> > >> the boot but then have a default AZ which has the HV from both AZ1 AND
> > >>AZ2
> > >> so that when the user does not specify any AZ in the boot command I
> > >>scatter
> > >> my VM on both the AZ in a balanced way.
> > >>
> > >
> > >I do not understand your goal. When you create two availability-zones
> and
> > >put ALL of your compute nodes into these AZs, then if you don't
> specifies
> > >the AZ in your request, then AZFilter will automatically accept all
> hosts.
> > >The defaut weigher (RalWeigher) will then distribute the workload
> fairely
> > >among these nodes regardless of AZ it belongs to. Maybe it is what you
> > >want?
> >
> >   With Havana that does not happen as there is a concept of
> > default_scheduler_zone which is none if not specified and when we specify
> > one can only specify a since AZ whereas in my case I basically want the 2
> > AZ that I create both to be considered default zones if nothing is
> > specified.
>
> If you look into the code of the AvailabilityFilter, you'll see that the
> filter automatically accepts host if there is NO availability-zone in the
> request, which is the case when user does not specify AZ. This is exactly
> what I see in my Openstack platform (Hanava stable). FYI, I didn't set up a
> default AZ in config. So whenever I creates several VMs without specifying
> an AZ, the scheduler spreads the VMs into all hosts regardless of their AZ.
>
> What I think lacking is that user can not select a set of AZs instead of
> one or none right now.
>
> > >
> > >> Any pointers.
> > >>
> > >> Thanks,
> > >> Sangeeta
> > >>
> > >> _______________________________________________
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> > >> OpenStack-dev at lists.openstack.org
> > >> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> > >>
> > >
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> >
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>
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