Clusters are usually deployed to improve performance and availability over that of a single computer, while typically being much more cost-effective than single computers of comparable speed or availability.[SUP][1][/SUP]
Please read this wiki article in general and same concept works every where not only just webMethods IS and for any web servers
[URL]http://en.wikipedia.org/wiki/Computer_cluster[/URL]
Based on the above you will get some idea and proceed with clustering setup if at all required per your server environment and HA needs which can help ebusiness up and running smooth:
HTH,
RMG
#webMethods#webMethods-General#Integration-Server-and-ESB