Document Ceilometer Agent Central in HA

Explain how to bring highly available Ceilometer Agent Central service
in the active / passive section.

In this manual, the service is installed on API nodes and is managed by
Pacemaker cluster manager.

Change-Id: I1653ffe4908918efbb3beeac036abd8581432dcb
Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>
Warn operators not to install openvswitch-brcompat

The LibvirtHybridOVSBridgeDriver VIF driver for the Open vSwitch Neutron
plugin needs to create a Linux bridge using brctl for the iptables firewall
rules that implement security groups. But if the package
openvswitch-brcompat is installed, brctl actually creates an OVS bridge and
the security groups won't work.

bug: #1220358
Change-Id: Ia74ffbb4ed327af41f938f900fc105492606b50b
Adds a Cell scheduling section to the Compute Cells configuration.

Want to add admin user info on how to add a scheduler hint
to launch a new VM where you want to.

Also not sure if --woffset and --wscale are now in use.

Partial fix bug 1187290

Change-Id: I252577b15fd4ac30ed943cc6ffa015e7e3203909
Merge "Document Ceilometer Agent Central in HA"
Merge "Adds a Cell scheduling section to the Compute Cells configuration."
Merge "Warn operators not to install openvswitch-brcompat"