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On Fri, Dec 14, 2018 at 10:38 AM Torin Woltjer
<torin.woltjer at granddial.com> wrote:
>
> I've restarted the instances that I'm using to test but no luck.
>
> I have the setting set on just the highest compute node; I tried setting it on one of my older gen compute nodes as well but because there is production load on it, I am anxious about restarting services; I did restart the nova-compute service after making the change and there was no change in behavior. Should the setting also be set on the controllers?

I don't believe you need it on the controllers. The host capabilities
get registered by nova-compute, so the controller config wouldn't make
use of those settings. I wouldn't have different CPU modes though. If
you're going to hard set one, you should hard-set them all. Just the
difference between custom and passthrough may be enough to make nova
reject the request.

You should be able to easily set the custom setting on the production
node and restart nova-compute without affecting running instances.
Once the instances are running, nova has very little to do with them.
As mentioned before, all the settings are applied at boot. The only
caveat to this I can think of is if you're running NFS shared storage
and nova services are in docker containers. I have seen this cause
root disks of instances to go read-only as the mounting of the NFS
volume comes and goes with the container. I've done exactly this
multiple times with ceph-backed instances running on both baremetal
and containerized hosts with no issues.

>
> When I look at virsh capabilities there is certainly a difference between the two
> 7c7
> <       <model>Opteron_G5</model>
> ---
> >       <model>Opteron_G4</model>
> 9c9
> <       <microcode version='100665426'/>
> ---
> >       <microcode version='100664894'/>
> 15d14
> <       <feature name='bmi1'/>
> 25c24
> <       <feature name='tce'/>
> ---
> >       <feature name='lwp'/>
>
>
> I look at the test instance on the compute node with the G5 opteron and this is in the XML
>   <cpu mode='custom' match='exact' check='full'>
>    <model fallback='forbid'>Opteron_G4</model>
>    <topology sockets='1' cores='1' threads='1'/>
>    <feature policy='require' name='vme'/>
>    <feature policy='require' name='x2apic'/>
>    <feature policy='require' name='hypervisor'/>
>    <feature policy='disable' name='rdtscp'/>
>  </cpu>
>
> This looks like it is correctly taking the CPU model that I have specified in nova.conf, yet it does not want to migrate to the Opteron_G4 node.