WebSphere Application Server V7.0: Concepts ... - IBM Redbooks

Note: Each Load Balancer installation can host multiple cluster addresses.
You do not necessarily need a separate installation for each cluster
address.
► Two reverse proxy servers
Both of the reverse proxy servers (running on System C and System D) are
receiving requests from the Load Balancer and share the requests coming
from the clients. Each proxy server is installed on a different system to provide
a maximum level of redundancy. Keep in mind that both reverse proxy servers
must have an identical configuration.
► Two Web servers
Each Web server, one running on System G and the other one on System H,
receives requests from the second Load Balancer cluster and shares the
requests that come from the reverse proxies. Each Web server is installed on
a different machine but they must have an identical configuration.
► An application server cluster
The cluster is spread across four server systems and implements a
combination of vertical and horizontal scaling. The cluster consists of eight
cluster members, two on each server. Although the application servers are
grouped together in one cluster, they might originate from different
installations. The application servers on System I, for example, could be two
separate installations of WebSphere Application Server. The application
servers on System J could be profiles of a single installation.
► Two database servers
The database servers need to be made highly available using database
system specific tools or operating system-based clustering software.
► Two LDAP servers
The LDAP servers could use a high availability software product (like another
Load Balancer) or the backup LDAP server support (as provided through
federated repositories user registry in WebSphere Application Server). The
LDAP servers must have identical structure and user population.
This topology is designed to maximize performance, throughput, and availability.
It incorporates the benefits of the other topologies that have been discussed
earlier in this chapter.
162 WebSphere Application Server V7.0: Concepts, Planning, and Design