[Pacemaker] System Health

[Andrew Beekhof]

On May 8, 2009, at 10:00 PM, Mark Hamzy wrote:
>
> > Then I'd add
> > - node-base-score
> > Which cuts out half of the rsc_location constraints and seems like a
> > generically useful concept.
> > (One would probably look up this value and set node-weight during
> > unpack_nodes() )
> > I still debating whether this is suitable for 1.0
>
> Could you explain more here (and give an example), please? I am
> new to HA and feel that I must be missing something.
>
> All nodes start at zero unless some rule is defined to give them
> a weight. Are you proposing that they would start at some
> user-defined value? For example, 100?
>
s/would/could/ but basically yes.
> >
> > I don't consider this a huge configuration overhead, BUT, I wouldn't
> > object to adding
> > - node-health-strategy = (none, custom, migrate-on-red, ...)
> >
> > * "none" would be the default
> > * "custom" would require the admin to configure the rsc_location
> > constraints manually
> > * "migrate-on-red" would be the one you're proposing and implicitly
> > create the relevant rsc_location constraints behind the scenes.
> > I'd not call it "automatic" in order to allow us to add other
> > "default" strategies in the future.
>
> Yes. "migrate-on-red" would automatically all variables that start
> with #health. This would reduce the chance of errors in forgetting
> a variable, adding a new monitored variable later on, or mispelling
> a variable.
>
> What is the difference between "none" and "custom"?
>

Right now, at an implementation level, nothing.
However "none" makes it absolutely clear to the admin that the feature  
is turned off.

It also allows "custom" to do something later on.

Come to think of it, "none" should probably make the node-health-score- 
* all default to zero.
> I image that a sysadmin could set "none" and still define only
> the #health variables that they are interested in the other_health
> rsc_location list.
>
> This would work the same as "custom". I imagine that you mean
> "custom" to possibly inform HA that these rules exist and are
> being used as intended (not to be defaulted in anyway).
>
Right, we could possibly report a configuration warning if someone  
selects "custom" but doesn't define any rules.