[Pacemaker] Reload action and stop/start sequence questions

[Vladislav Bogdanov]

27.07.2011 05:25, Andrew Beekhof wrote:
...
>> * Dependent resources should not be stopped/started for 'reload' action.
>> Of course they are restarted if reload fails and stop/start is executed
>> then. (I see that they are restarted now for reload of a resource they
>> depend on, is it a bug?)
> 
> More like a limitation.  Which is a round-a-bout way of saying "really
> hard to fix bug".
> You're welcome to create a BZ for it though, maybe one day I'll figure
> out how to resolve it.
> 
>> * (wish) Resources should be migrated out of node (if they support live
>> migration) for stop/start sequence of resource they depend on.
> 
> Migration can only occur if a resource at the bottom (excluding any
> clones) of the resource stack.
> In order to migrate any colocation dependancies need to be running at
> _both_ the old and the new locations.
> 
> This can only be true for resources that depend on clones.

Yep, I actually had clones in mind.

> 
>> * (wish) Redefinition of clones should be handled in a way which allows
>> dependent live-migratable resources to survive (if reload action for
>> clone instance either is not supported or fails).
> 
> This doesn't make sense.
> If the definition of one clone changes, then they all change and there
> is nowhere for dependant resources to migrate to.

Yes, I understand your point. That's why I marked this as a wish. It
would be a killer feature - serialization of clone instances restarts.

> 
>> That is: dependent
>> resources which support live migration are first tried to migrate out of
>> one node, and are stopped if migration fails. Then clone instance is
>> restarted on that node. Then the same procedure applies to next cluster
>> node so resources may return back to a first node.
>>
>> If above (at least first three points) is right, then is it possible to
>> get a set of previous instance parameters the same way new configuration
>> is passed (env vars), or RA should save that information itself in advance?
>>
>> Best,
>> Vladislav
>>
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> 
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