On 2012-11-12T14:03:24, David Vossel <dvos...@redhat.com> wrote:
> > We want "A" to be restarted if "B" fails. (If A->B are also
> > collocated, we'd also get fail-over after migration-threshold
> > triggers. That may not always be desired.)
> I'm not sure I follow why we'd be concerned about migration-threshold
> here. The only situation I can think of were migration-threshold
> could cause weird behavior is if someone sets a migration threshold on
> the children but not on the parent, but that seems like a
> configuration problem to me.
I was saying that we don't need to concern ourselves about them,
actually.
If rsc-vm1 and vm1-http are collocated (in addition to being ordered
with the magic flag), the Nth failure of the web service will trigger
the rsc-vm1 to be moved along with vm1-http, which is desired.
> > A "restart-origin" attribute, perhaps?
> Would this attribute need to be exposed through the configuration?
>
> I was thinking this constraint would be an implied relationship
> between the container parent and members internally. We probably
> already have the right set of flags internally in the pengine to
> represent this sort of constraint. If we don't need to expose this
> logic to the config my vote is to limit it to the container use case
> for now.
I was thinking that the constraint - either as a flag to the order
constraint or a new one - *would* be the configuration syntax.
I don't so much like a new container object. That was one of the things
that were wrong with "groups", design-wise. The grouping/relationships
of objects belong into the constraints section.
A new attribute to the order constraint is also fully and completely
backwards compatible with any and all tools we're using today.
A container object means that we need to teach each and every tool about
them again; that one can reference the primitives they contain in
dependencies, etc.
Regards,
Lars
--
Architect Storage/HA
SUSE LINUX Products GmbH, GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer, HRB
21284 (AG Nürnberg)
"Experience is the name everyone gives to their mistakes." -- Oscar Wilde
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