[kolla-ansible][nova]Problem with distribution of instance on servers

Laurent Dumont laurentfdumont at gmail.com
Wed Feb 16 01:00:14 UTC 2022

In a healthy setup, should build_failure_weight_multiplier be triggered?

>From the doc, tweaking this might mean you try to schedule and
built instances on computes that are not healthy.

On Tue, Feb 15, 2022 at 6:38 PM Tony Liu <tonyliu0592 at hotmail.com> wrote:

> Enable debug logging on nova-scheduler, you will see how the winner is
> picked.
> I had the same issue before, caused by the build-failure weigher enabled
> by default.
> setting build_failure_weight_multiplier to 0 resolved issue for me.
> Instances are
> balanced by weighers (compute and memory) as expected.
> shuffle_best_same_weighed_hosts and host_subset_size are not necessary,
> unless
> it's required by certain cases.
> Tony
> ________________________________________
> From: Laurent Dumont <laurentfdumont at gmail.com>
> Sent: February 15, 2022 12:54 PM
> To: Franck VEDEL
> Cc: openstack-discuss
> Subject: Re: [kolla-ansible][nova]Problem with distribution of instance on
> servers
> There are two settings we've tweaked in the past in Nova.
> shuffle_best_same_weighed_hosts  --> Allow more spreading in the case of
> computes with the exact same specs/weights.
> host_subset_size --> Helps with concurrent requests to get different hosts
> Before that, we saw the same behavior with Openstack stacking VM on single
> computes. It still respects anti-affinity, but I don't see a good reason to
> not spread as a default. Changing these two was enough to allow our spread
> to get a little better.
> On Tue, Feb 15, 2022 at 11:19 AM Franck VEDEL <
> franck.vedel at univ-grenoble-alpes.fr<mailto:
> franck.vedel at univ-grenoble-alpes.fr>> wrote:
> Hello,
> I seem to have a problem that I hadn't seen.
> I have 3 servers for my openstack, built with Kolla-ansible, I'm in
> Victoria version.
> I had simply put the 3 servers in the [compute] part of the multinode
> file, at first it worked, but for some time all the VMs are placed on
> server 1.
> The 3 servers are operational, identical. here are 3 screenshots to show
> it. (on the images, the instances on servers 2 and 3 are present because it
> worked correctly, but no more instances are created on these servers now)
> [cid:17eff2778356f37a4481]
> [cid:17eff277835e47aa83c2]
> [cid:17eff2778356f53d34a3]
> I tried to understand how the instances are distributed on the servers,
> but in my case, I don't understand why none are assigned to the 2nd and 3rd
> server.
> How to find the problem? It should be nova-scheduler . Do you have to do
> anything special? Go see if a parameter has a bad value?
> Thanks in advance if you can help me.
> Franck VEDEL
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