[ClusterLabs] Coming in Pacemaker 2.0.1: build-time default for resource-stickiness

[Ken Gaillot]

Hello all,

I hope to have the first Pacemaker 2.0.1 release candidate ready next
week!

A recently added feature is a new build-time option to change the
resource-stickiness default for new CIBs.

Currently, resource-stickiness defaults to 0, meaning the cluster is
free to move resources around to balance them across nodes and so
forth. Many new users are surprised by this behavior and expect sticky
behavior by default.

Now, building Pacemaker using ./configure --with-resource-stickiness-
default=<N> tells Pacemaker to add a rsc_defaults section to empty CIBs
with a resource-stickiness of <N>. Distributions and users who build
from source can set this if they're tried of explaining stickiness to
surprised users and expect fewer users to be surprised by stickiness.
:)

Adding a resource default to all new CIBs is an unusual way of changing
a default.

We can't simply leave it to higher-level tools, because when creating a
cluster, the cluster may not be started immediately and thus there is
no way to set the property. Also, the user has a variety of ways to
create or start a cluster, so no tool can assume it has full control.

We leave the implicit default stickiness at 0, and instead set the
configured default via a rsc_defaults entry in new CIBs, so that it
won't affect existing clusters or rolling upgrades (current users won't
see behavior change), and unlike implicit defaults, users can query and
remove resource defaults.
-- 
Ken Gaillot <kgaillot at redhat.com>