Sort instances if possible inside an host aggregate¶
Note
This spec was abandoned by efried on account of having been sitting in the backlog directory since 2015.
https://blueprints.launchpad.net/nova/+spec/same-instances-scheduling
Nova should allow sorting instances based on preferences without host aggregate speraration.
Problem description¶
As an operator, when you manage hundred or thousand nodes, instances will be automatically balanced though all nodes. There is no possibility to ask the infrastructure to group a kind of instances on the same hosts if possible.
A kind of instance could be based on a specific image, a specific flavor.
For this use case, host-aggregates are not used because this is not a strong constraint, this is a prefered situation.
Use Cases¶
Reduce the licence cost: Microsoft Windows licences are billed by host or by socket. The goal is to stack all Windows instances on the same hosts as much as possible.
As much as possible means this is a best effort feature, if Nova can place this new Windows instance on a compute where other Windows are running, do it. If not, spawn it where you want or on a empty compute to identify it as preferred widows compute for future windows spawn.
Proposed change¶
Posting to get preliminary feedback on the scope of this spec.
Alternatives¶
None
Data model impact¶
None
REST API impact¶
None
Security impact¶
None
Notifications impact¶
None
Other end user impact¶
None
Performance Impact¶
None
Other deployer impact¶
None
Developer impact¶
None
Implementation¶
Assignee(s)¶
None
Work Items¶
None
Dependencies¶
None
Testing¶
None
Documentation Impact¶
None
References¶
None
History¶
None
Release Name |
Description |
|---|---|
Liberty |
Introduced |
Train |
Abandoned |
