Nova-Cells-v2

Nova Cells v2

Bugs

• https://bugs.launchpad.net/openstack-manuals/+bug/1673616 - Scaling in Operations Guide - cells section needs to be updated
• https://bugs.launchpad.net/nova/+bug/1682060 - empty nova service and hypervisor list
  • Fixed with a docs patch: https://review.openstack.org/#/c/456923/ (mriedem)
• https://bugs.launchpad.net/nova/+bug/1682693 - tags and not-tags cannot work properly
  • Patch from Kevin Zheng: https://review.openstack.org/#/c/456872/ - needs to be backported to ocata and newton
• https://bugs.launchpad.net/trove/+bug/1682845 - nova's server group API returns deleted instances as members
  • Original regression is reverted: https://review.openstack.org/#/c/457097/
  • TODO(dansmith) to provide a proper fix

TODOs

• Older tracking etherpads (these may be out of date):
  • https://etherpad.openstack.org/p/cellsV2-remaining-work-items
  • https://etherpad.openstack.org/p/nova-multiple-cells

Open Questions

• Should the computes self-register with a cell when the compute_nodes record is created from the ResourceTracker? https://review.openstack.org/#/c/369634/
  • How would the computes know which cell to map to? We could add something to the model to flag a 'default' or 'staging' cell mapping, or put something into nova.conf on the compute node.
  • If we auto-register into a default/staging cell, how do we move hosts to other cells? nova-manage CLI?
  • We have an option to auto-map hosts from the scheduler since Ocata, with improvements being made in Pike: https://blueprints.launchpad.net/nova/+spec/discover-hosts-faster

Manifesto

http://docs.openstack.org/developer/nova/cells.html#manifesto

Testing

https://etherpad.openstack.org/p/nova-cells-testing

DB Table Analysis

https://etherpad.openstack.org/p/nova-cells-table-analysis

Scheduling requirements

https://etherpad.openstack.org/p/nova-cells-scheduling-requirements

Code Review

• https://review.openstack.org/#/q/topic:bp/cells-scheduling-interaction
• Otherwise see the cells v2 section in the Ocata review priorities etherpad: https://etherpad.openstack.org/p/ocata-nova-priorities-tracking
• https://review.openstack.org/#/q/status:open+project:openstack/nova+branch:master+topic:man

References

• Note the original cells wiki is here: https://wiki.openstack.org/wiki/Blueprint-nova-compute-cells
• Kilo design summit etherpad: https://etherpad.openstack.org/p/kilo-nova-cells
• nova-specs: https://review.openstack.org/#/q/status:open+project:openstack/nova-specs+branch:master+topic:bp/cells-instance-mapping,n,z
• Flow diagrams: http://paste.openstack.org/show/144068/
  • https://etherpad.openstack.org/p/nova-cells-flow-diagram commentable version