Question : Which Clustering Solution should I use

We are developing a B2C web application where High Availabilty and  Scalability are two main criteria. We are thinking of using load balancing and clustering to achieve this aim. We are using load balancing and clustering to implement the 3 clusters tiers, namely Web Server tier, Application tier and database tier.  We have decided to use MySQL Enterprise for the database tier.
Note: Each cluster will have a load balancer.

However, we are undecided on the clustering for the first two tier.
1.      Using Apache TOMCAT for the web server cluster and JBOSS AS as the Application cluster OR
2.      Using just one cluster for the first two tiers – JBOSS AS cluster with embeded Tomcat.
Please recommend which is the better option and why.

Aside
1.      Can we use normal NAS storage for the database tier and still achieve HA and Long term Scalability, and why?
2.      Do we use the load balacing software that comes with the OS ? Or do we use other software or hardware load balancer?   And Why?

Answer : Which Clustering Solution should I use

hi,

if you realy need a highly available infra for your application you can use :
.a cluster of 2 or 3 apache servers (not tomcat) in front of your application tier. Place a load balancer in front of the apache servers.
.a cluster of 3 jboss servers for the application tier.

3 servers will still provide load balancing even one of them fails.

Hardware load balancers will be more efficient but a little bit harder to setup.

Emmanuel