[Pacemaker] Node attributes

[Johan Verrept]

On Tue, 2009-09-08 at 17:01 +0200, Florian Haas wrote:
> > As mentioned in my other post, it works as long as you do not have
> > multiple reasons to move your master. If you do, you limit the priority
> > space. This is not a problem in simple cases but it will be in more
> > complex configurations, especially when you have more than one RA using
> > crm_master and no ways to influence which priority values they assign
> > without modifying them (with all the upgrade fun that entails).
> 
> crm_master always applies on a per-resource, per-node basis. It
> absolutely wouldn't make sense to have one RA override the master pref
> of another.

True. I referred to colocated resources. Their priorities are added and
then the values start mattering a lot more. The correct values cant
really be predicted by the RA writer, it all depends on how the admin
wants the resources to behave.

> > On my system, I have an external way to detect if my internet
> > connections are up or not. I have written a simple RA that hooks into
> > this and changes a node attribute between "online" and "offline". This
> > is then interpreted with a location rule. It works and allows me to keep
> > my priorities all within my cib.
> 
> Why do you need to write an RA for that -- doesn't pingd already do what
> you need?

It does, actually. I just prefer to have a single mechanism to determine
the state of my network connections. It was easier to import the
existing mechanism in pacemaker than the other way around.

	J.