[openstack-dev] [nova][ironic] Concerns over rigid resource class-only ironic scheduling
Matt Riedemann
mriedemos at gmail.com
Thu Sep 7 19:57:24 UTC 2017
On 9/7/2017 2:48 PM, Nisha Agarwal wrote:
> Hi Ironic Operators,
>
> From Pike, ironic nodes get scheduled based on just the resource class
> from nova. Do you guys see any concerns over this "rigid resource class
> only ironic scheduling"?
>
> To be more specific, at your datacentre/production environment what all
> filters are configured in nova.conf (configuration file for nova) for
> scheduling an ironic node? Do you use RamFilter/DiskFilter/CoreFilter in
> the "use_baremetal_filters" for ironic nodes scheduling from nova?
>
> Thanks and Regards
> Nisha
>
>
>
> __________________________________________________________________________
> OpenStack Development Mailing List (not for usage questions)
> Unsubscribe: OpenStack-dev-request at lists.openstack.org?subject:unsubscribe
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>
Some more background information is in the ironic spec here:
https://review.openstack.org/#/c/500429/
Also, be aware of these release notes for Pike related to baremetal
scheduling:
http://docs-draft.openstack.org/77/501477/1/check/gate-nova-releasenotes/1dc7513//releasenotes/build/html/unreleased.html#id2
In Pike, nova is using a combination of VCPU/MEMORY_MB/DISK_GB resource
class amounts from the flavor during scheduling as it always has, but it
will also check for the custom resource_class which comes from the
ironic node. The custom resource class is optional in Pike but will be a
hard requirement in Queens, or at least that was the plan. The idea
being that long-term we'd stop consulting VCPU/MEMORY_MB/DISK_GB from
the flavor during scheduling and just use the atomic node.resource_class
since we want to allocate a nova instance to an entire ironic node, and
this is also why the Exact* filters were used too.
There are more details on using custom resource classes for scheduling here:
https://specs.openstack.org/openstack/nova-specs/specs/pike/approved/custom-resource-classes-in-flavors.html
Nisha is raising the question about whether or not we're making
incorrect assumptions about how people are using nova/ironic and they
want to use the non-Exact filters for VCPU/MEMORY_MB/DISK_GB, which as
far as I have ever heard is not recommended/supported upstream as it can
lead to resource tracking issues in Nova that eventually lead to
scheduling failures later because of the scheduler thinking a node is
available for more than one instance when it's really not.
--
Thanks,
Matt
More information about the OpenStack-dev
mailing list