Hi clint, matt. To be noticed that post-copy and auto-convergence are mutually exclusive.
The drawbacks that we experienced with here is that live-migration using either way post-copy or auto-convergence will likely fail for application not being able to handle throttling. Although, post-copy is guaranteed to work for most of your migration. On the design part of your solution. For a while we had the same design with each rack being segmented but we gave up with this choice as it was a PITA especially for live-migration. We’re currently migrating our network design to a much simplified all L3 network layout with our underlying network a bgp driven network and all overlay network being managed by Openstack. Let me know if you need more details or information. Kind regards, G. Le mar. 7 août 2018 à 01:44, Matt Riedemann <mriede...@gmail.com> a écrit : > 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 > > _______________________________________________ > OpenStack-operators mailing list > OpenStack-operators@lists.openstack.org > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators >
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