On 03/21/2016 06:22 AM, Miguel Angel Ajo Pelayo wrote:
Hi,

    I was doing another pass on this spec, to see if we could leverage
it as-is for QoS / bandwidth tracking / bandwidth guarantees, and I
have a question [1]

    I guess I'm just missing some detail, but looking at the 2nd scenario,
why wouldn't availability zones allow the same exactly if we used one
availability zone per subnet?

   What's the advantage of modelling it via a generic resource pool?

Hi Miguel,

On the (Nova) scheduler side, we don't actually care whether Neutron uses availability zone or subnet pool to model the boundaries of a pool of some resource. The generic-resource-pools functionality being added to Nova (as the new placement API meant to become the split-out scheduler RESTful API) just sees a resource provider UUID and an inventory of some type of resource.

In the case of Neutron QoS, the first thing to determine would be what is the resource type exactly? The resource type must be able to be represented with an integer amount of something. For QoS, I *think* the resource type would be "NIC_BANDWIDTH_KB" or something like that. Is that correct? This would represent the amount of total network bandwidth that a workload can consume on a particular compute node. Is that statement correct?

Now, the second thing that would need to be determined is what resource boundary this resource type would have. I *think* it is the amount of bandwidth consumed on a set of compute nodes? Like, amount of bandwidth consumed within a rack? Or some similar segmentation of a network, like an aggregate, which is a generic grouping of compute nodes. If so, then the bandwidth resource would be considered a *shared* resource, shared among the compute nodes in the aggregate. And if this is the case, then generic-resource-pools are intended for *exactly* this type of scenario.

Best,
-jay

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