Open Stack

On 8/6/2018 8:12 AM, Clint Byrum wrote:
> First a few facts about our installation:
> 
> * We're using kolla-ansible and basically leaving most nova settings at 
> the default, meaning libvirt+kvm
> * We will be using block migration, as we have no shared storage of any 
> kind.
> * We use routed networks to set up L2 segments per-rack. Each rack is 
> basically an island unto itself. The VMs on one rack cannot be migrated 
> to another rack  because of this.
> * Our main resource limitation is disk, followed closely by RAM. As 
> such, our main motivation for wanting to do live migration is to be able 
> to move VMs off of machines where over-subscribed disk users start to 
> threaten the free space of the others.

What release are you on?

> 
> * Do people have feedback on live_migrate_permit_auto_convergence? It 
> seems like a reasonable trade-off, but since it is defaulted to false, I 
> wonder if there are some hidden gotchas there.

You might want to read through [1] and [2]. Those were written by the 
OSIC dev team when that still existed. But there are some (somewhat 
mysterious) mentions to caveats with post-copy you should be aware of. 
At this point, John Garbutt is probably the best person to talk to about 
those since all of the other OSIC devs that worked on this spec are long 
gone.

 >
 > * General pointers to excellent guides, white papers, etc, that might 
help us avoid doing all of our learning via trial/error.

Check out [3]. I've specifically been meaning to watch the one from 
Boston that John was in.

[1] 
https://specs.openstack.org/openstack/nova-specs/specs/pike/approved/live-migration-force-after-timeout.html
[2] 
https://specs.openstack.org/openstack/nova-specs/specs/pike/approved/live-migration-per-instance-timeout.html
[3] https://www.openstack.org/videos/search?search=live%20migration

-- 

Thanks,

Matt