[Linux-cluster] Two node cluster - howto

[Lon Hohberger]

On Mon, 2007-10-29 at 00:20 +0000, Andrew Hole wrote:
> Hello!
> 
> II want to create a very basic cluster of two nodes to configure
> failover of a service. This
> service is very simple, without shared storage. Basically if the
> service fails in a node, I want
> to ensure availability on the other node.
> I would like to clarify some doubts:
> - I need to use quorum disk?

If you have no shared storage, then a quorum disk is rather
impossible ;)  (You don't need one.)

> - And about fince device? I need to setup a fince device?

Under most circumstances, you do not need a fence device if you do not
have any shared storage, but it can be helpful.  Fencing exists to
prevent data corruption on shared media.

ex: node A goes to sleep with a write lock held...
    node B thinks node A is dead, takes over, and acquires the same lock
a-> node A wakes up still thinking its lock is valid
b-> node A continues writing
    (doom)

Power fencing prevents (a) (and therefore (b))
SAN-level fencing prevents (b)

> - Exists some example of using Cluster to configure a simple two nodes cluster?

http://sources.redhat.com/cluster/faq.html 

http://sources.redhat.com/cluster/doc/nfscookbook.pdf

-- Lon