[DRBD-user] migration strategy?

[Miles Fidelman]

Hi Folks,

I've been running a 2-node HA cluster for several years - Xen VMs backed 
by DRBD volumes + pacemaker for failover.

I've recently added 2 newer nodes, and I'm trying to figure out the most 
straightforward way to migrate a couple of production VMs from the old 
hardware to the new hardware - with minimum outage.

Just to complicate things a bit, I'm running DRBD 8.0.14 - which doesn't 
support a 3-node configuration.

Any suggestions re. a sequence of operations that allows me to:
1.  install latest versions of everything (Debian, DRBD, Xen, Pacemaker, 
etc.) on the new nodes (easy)
2.  replicate data volumes to the new nodes while the VMs continue to 
run on the old nodes
3.  migrate the VMs to the new nodes
4.  decommission the old nodes

- all with minimal downtime for the VMs, and minimal (or no) period 
where I don't have a backup copy of the data?

Thanks much,

Miles Fidelman

-- 
In theory, there is no difference between theory and practice.
In<fnord>  practice, there is.   .... Yogi Berra