[Discuss] Redundant array of inexpensive servers: clustering?

[Richard Pieri]

Kent Borg wrote:
> Not a high performance model but a high availability model that doesn't
> care much about what happens inside the VMs. A given VM that isn't
> otherwise interested in rebooting might be run for years in such a rig.

A more detailed plan for the basic Xen + checkpoint + DRBD configuration 
I described.

It also has the same flaw: split brain. There's no quorum, and you can't 
get a quorum with DRBD. You have to have a third node to break ties. 
Alternatively, you can use a chunk of shared storage that can be locked 
by a single node: when the heartbeat fails the two nodes race to see 
which can lock the shared storage. Whichever gets the lock is the live 
node. You can't do this with DRBD. You need multipath storage and that's 
not cheap.

-- 
Rich P.