[Pacemaker] Multiple node loadbalancing

[Lars Ellenberg]

On Wed, Jul 30, 2014 at 02:59:31PM +0200, Machiel wrote:
> Hi Guys
> 
>     We are trying to setup the following, however we can not seem to
> find any references on the internet which will explain on how to
> configure it.
> 
>     We have 3 machines, and we need to setup load balancing on the
> machines as follows:
> 
>             - Load balancer and apps running on all 3 machines
>             - 1 machine should be the load balancer (master) which
> will balance traffic over all 3 machines including itself.
>             - should this node fail, the second node should take
> over the task, and if the second node should fail, then the 3rd node
> should take over as standalone until the other nodes are restored.
> 
>         We are only able to find configuration instructions on how
> to setup load balancing for 2 nodes which we have done several
> times, however no info for 3 nodes.
> 
> 
>         We are currently using ldirectord and heartbeat, however in
> this setup, if the first node fails , then both the 2nd and 3rd
> nodes try to take over. (this was configured very long ago though).

While the communication and membership layer of heartbeat always
supported "many" nodes, the "resource manager" part of heartbeat
(haresources mode) is a very basic shell script, and does only support
two-node clusters.

With haresources mode of heartbeat,
you can only do two-node clusters
(if you intend to keep your sanity).

>         I would really appreciate any suggestions on this or even
> links where I can find the information would be appreciated.

Use pacemaker.

Whether you want heartbeat or corosync
as the communication an membership layer is up to you.

For new installations and recent OS releases,
pacemaker + corosync is generally the recommended way.

-- 
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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