Happy Mothers Day!
So – today’s topic: Switching Pool Masters with High Availability.
The Pool Master/Primary Server is the Chief. The Boss. El Jeffe. The proverbial workhorse for things “XAPI and Xen”: from monitoring subordinates to responding to XenCenter requests we make with each click. For whatever reason, well, you find it is time to elect a new Pool Master.
This is where we stop before “doing” because if you have High Availability (HA) enabled then you must disable it before electing a new Pool Master!
I use bold text to drive the point home, save some pain, and lead into the Why? and How?
Well, with HA enabled and switching Pool Masters it can appear to the pool that… a server is down and HA will kick in. This can lead to all sorts of nastiness and confusion because:
HA is doing what it is supposed to do when a server is in a non-active state
HA will work itself (some times to death) trying to implement the desired configuration
HA is not confused, but ill-informed that the non-active state/switch of a Pool Master was with Administrative Purpose
So, how to we disable HA before we swap out Pool Masters? There are two ways:
A. The Command Line
From the current Pool Master, use the command line to execute:
And if you are paranoid like myself, you can run that command on every other pool member as well!
From XenCenter, you can select the Pool/Pool Master icon in question and from the HA tab, disable HA from there.
So, there we have it! Once HA is disabled, switch Pool Masters and when all servers are in an active state: re-enable HA from XenCenter or from the command line:
And this is from my Virtual Desktop to you!