Live migration fails despite matching CPUs
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
OpenStack Compute (nova) |
Fix Released
|
High
|
Andrew Bonney | ||
Train |
Fix Released
|
High
|
Stephen Finucane | ||
Ussuri |
Fix Released
|
High
|
Stephen Finucane | ||
Victoria |
Fix Released
|
High
|
Stephen Finucane |
Bug Description
Having upgraded to Ussuri, we've noted that live migrations now always fail across our hosts with newer Intel CPUs (identified by libvirt as Cascadelake-
When processing the CPU's features, the calls made by Nova to libvirt appear to result in an XML segment which includes 'policy' keys for each feature which may be set to 'disable'. When Nova interprets this (see https:/
When a live migration is scheduled, these additional feature requirements are then passed to the remote host which compares with its running features and identifies they are incompatible, despite the CPUs being identical. As a result we're currently unable to live migrate any VMs between hosts which use these CPUs.
Further debug output is included in http://
Nova stable/ussuri 7d556106bfd3e64
Ubuntu 18.04
libvirt 6.0.0-0ubuntu8.
Changed in nova: | |
assignee: | nobody → Kashyap Chamarthy (kashyapc) |
Changed in nova: | |
status: | New → In Progress |
tags: | added: libvirt |
Changed in nova: | |
assignee: | Kashyap Chamarthy (kashyapc) → Andrew Bonney (andrewbonney) |
Changed in nova: | |
importance: | Undecided → High |
For reference we've temporarily worked around this with the following patch. Whilst this won't be comprehensive enough to contribute, it has proved sufficient to resolve the issue across our deployments.
https:/ /github. com/bbc/ nova/commit/ 9d11ce63640dc08 d2c69ff2176156d 2887f1039f