Clustering

Horizontal Clustering

Horizontal clustering. A horizontally clustered environment contains multiple physical machines (nodes); see Horizontally clustered environments for more information.

A horizontally clustered environment contains multiple physical machines (nodes), as illustrated in the previous section (Architectural overview of a clustered environment) The cluster-enabled application is deployed to each node and is available for requests. An IP-Sprayer (load balancer (IP Sprayer) provides workload management by distributing requests to the various nodes. A horizontal cluster 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 should not exceed the number of supported management agents in a single server environment because the management server cannot handle the load.

Advantages :
Provides hardware failover.
Provides all the advantages of a vertical cluster .
Scales.
Can be used in conjunction with vertical clusters.

Disadvantages :
Additional machines require more installation and maintenance.


Vertically clustered environments


Vertical Clustering

Vertical clustering.

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.

Advantages :

Provides process failover.
Increases efficiency with multiple Java(TM) Virtual Machines .
Provides load balancing through workload management.

Disadvantages


Offers minimal scalability.
Does not provide hardware-level failover.


The following shows an example of a vertically clustered environment:



Horizontal and Vertical clusters can be worked in combination