Open Stack

> If we now resize the instance to a different flavor which has a
> different set of traits, we would end up with a new set of traits,
> which map a new set of deploy templates, with a new set of steps.
> 
> How do we apply this change? Should we execute all matching deploy
> steps, which could (e.g. RAID) result in losing data? Or should we
> attempt to execute only those deploy steps that have changed? Would
> that always work? I don't think we keep a record of the steps used to
> provision a node, so if templates have changed in the intervening time
> then we might not get a correct diff.

Not being intimately familiar with the workings, the approach I've been
advocating is to only support the changes you support, and fail on
anything else.

In other words, compare the old flavor to the new flavor. If the diff
contains anything other than this "hyperthreading" gizmo, fail.

Ironic resize is a special snowflake, and only supports a very limited
set of changes done in a very limited way. At first, it's just one
thing. You can add other pieces as demand arises, but by default you're
rejecting big complicated things like your RAID example.

efried
.