Open Stack

On 07/03/2014 10:13 PM, Mike Spreitzer wrote:

> I do think the issue these address --- the need to get application logic
> involved in, e.g., shutdown --- is most of what an application needs;
> involvement in selection of which member(s) to delete is much less
> important (provided that clean shutdown mechanism prevents concurrent
> shutdowns).

I assume this is more of the whole "cattle" model, where an instance 
could disappear at any time so applications should design for that?

As an alternate viewpoint, if a particular instance in a group is 
working on something "expensive" (long-running, difficult to checkpoint, 
etc.), maybe it would make sense to allow the application to help make 
the decision on which instance to shut down (or possibly even veto/delay 
the scale down operation).  If it takes a minute to finish the 
operation, and 15 minutes to redo it on another instance...

Chris