[Openstack-operators] [nova][scheduler] Specifying Qualitative requirements for a VM

Mathieu Gagné mgagne at calavera.ca
Tue May 10 16:10:41 UTC 2016

On Tue, May 10, 2016 at 11:53 AM, Ed Leafe <ed at leafe.com> wrote:
> Currently we load both quantitative (how much disk, RAM, etc) and qualitative (SSD vs. spinning, special chipsets, etc.) into the flavor that a user can request. As the number of qualitative features has been increasing, there is the phenomenon of “flavor explosion”, where each combination of compute resources with each possible qualitative feature results in an exponential growth in the number of required flavors. I have a spec [0] that is one of the first steps to address this by separating out qualitative features from flavors.
> Since many deployments use flavor as the equivalent of a SKU, this means that billing will now have to be modified to account for flavor + features instead of flavor alone. I’d like to start a discussion to better understand the implications of these proposed changes so that we can come up with the best approach to balance the respective needs.
> [0] https://review.openstack.org/#/c/313784/

Thanks for starting this thread. I'm glad someone is tackling this issue.

I would like baremetal flavor use cases to be included into the spec
so we can cover all bases.

In fact, I think this problem is even more relevant with baremetal
flavors where the explosion is exponential each time you add a
qualitative. You can easily end up with a 4x4x4 matrix or larger. This
is truer when you include all combinaison of RAID levels with nodes
with lot of disks.

I will make sure to comment with those details in the spec.


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