Page History

...

<Describe how the problem is fixed. Include all affected components. Include diagrams for clarity. This should be the longest section in the document. Use the sections below to call out specifics related to each aspect of the overall system, and refer back to this section for context. Provide links to any relevant external information.>

A few design principles to get startedHere are the key design constraints:

1. Nodes in an HA group MAY have different node policies.
2. Adding a node to an HA Group MUST NOT terminate/restart running services.
3. Nodes MAY be placed into an HA Group after node registration.
4. A node MUST be in 0 or 1 HA Groups. A node MUST NOT be in more than 1 HA Group.
5. A node specifies the other nodes in it's HA Group by Id. All nodes in an HA Group MUST specify all the other nodes in the group. Can we get the exchange to enforce this part of the model?
6. A user MUST have permission to modify all the node's (resources) in an HA Group in order to form the group.
7. A service that is deployed to all the nodes in an HA Group MUST be upgraded in a rolling restart in order to avoid a complete outage of the service.
8. The node agent on nodes in an HA Group MUST be upgraded in a rolling restart in order to avoid a complete outage of the service and model deployment capability.

...