Hi All:
I am working for merging starlingx patch to nova project. There is a fix patch[1] which I cannot understand what scene it fixes. In the patch description, it is a bug fix for patch[2], “0024 - primary: server-groups best effort and group size “, and the best-effort functionality is similar to server-group soft-affinty  & soft-anti-affinty. Could anyone tell me their difference?

 As the 0111 patch says “However if a host is specified, there are some scenarios where the dest compute will be preset causing that  host to be included in the list of server group hosts thereby preventing the current live migration from scheduling”, I review the code in stx-nova/nova/conductor/tasks/live-migration.py[3], but I still don’t understand what the "some scenarios” are.


[1] https://github.com/starlingx-staging/stx-nova/blob/master/stx-patches/0111-Exclude-current-instance-when-checking-ser.patch
[2] https://github.com/starlingx-staging/stx-nova/blob/master/stx-patches/0024-primary-server-groups-best-effort-and-group-size.patch
[3] https://github.com/starlingx-staging/stx-nova/blob/master/nova/conductor/tasks/live_migrate.py


Best Regards
Kunpeng