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

Scaling
Scaling represents the ability of the system to grow as the load on the system
grows. There are multiple ways to achieve scaling. For example, multiple
machines can be configured to add processing power, improve security,
maximize availability, and balance workloads. Scaling may be vertical or
horizontal (Figure 5-1). Which you use depends on where and how the scaling is
taking place.
Daemon
Node
Agent
vertical
scaling
Server A
Deployment
Manager
Application
Server
Application
Server
Application
Server
Application
Server
Daemon
Node
Agent
horizontal
scaling
Figure 5-1 Vertical and horizontal scaling with WebSphere Application Server
► Vertical scaling
Vertical scaling involves creating additional application server processes on a
single physical machine or z/OS image, providing application server failover
as well as load balancing across multiple application servers. This topology
does not provide an efficient fault tolerance because a failure of the
operational system or the hardware on the physical machine itself might
cause problems to all servers in the cluster.
128 WebSphere Application Server V7.0: Concepts, Planning, and Design
Server B
Application
Server