Cluster
Horizontal Cluster
A horizontally
clustered environment contains multiple physical machines (nodes).
The cluster-enabled application is deployed to each node and is available for
requests. An IP-Sprayer (load
balancer) provides workload management by distributing requests to the various
nodes. A horizontally clustered environment is used for high availability of
the management server. In a cluster environment where there is only one active
management server, the number of supported management agents must not exceed
the number of supported management agents in a single server environment.
Advantages of horizontally clustered environments
include the following:
·
Hardware
failover
·
All
the advantages of a vertical cluster
·
Scales
well
·
Can
be used in conjunction with vertical clusters
The disadvantage of a horizontally clustered
environment is that it require additional machines with additional installation
and maintenance.
Vertical Cluster
A vertically clustered environment contains multiple application
server instances hosted on the same physical machine (node). The HTTP server
plug-in distributes requests to the various Web server instances for
processing. A vertical cluster is configured so only one server instance is
active at a given time.
The advantages of a vertically clustered environment
is as follows:
·
Provides
process failover
·
Increases
efficiency with multiple Java(TM) Virtual Machines
·
Provides
load balancing through workload management
The disadvantages of a vertical cluster are as follows:
·
Offers
minimal scalability
·
Does
not provide hardware-level failover
The following figure shows an example of a vertically
clustered environment:
