What is work load management

What is work load management


Workload management is the concept of sharing requests across multiple instances of a resource. Workload management techniques are implemented expressly for providing scalability and availability within a system. These techniques allow the system to serve more concurrent requests. Workload management allows for better use of resources by distributing load more evenly.

Components that are overworked, and therefore, perhaps a potential bottleneck, can be routed around with workload management algorithms. Workload management techniques also provide higher resiliency by routing requests around failed components to duplicate copies of that resource.

In WebSphere Application Server, workload management is achieved by sharing requests across one or more application servers, each running a copy of the Web application. In more complex topologies, workload management is embedded in load balancing technologies that can be used in front of Web servers.

Workload management (WLM) is a WebSphere facility to provide load balancing and affinity between nodes in a WebSphere clustered environment. WLM can be an important facet of performance. WebSphere uses WLM to send requests to alternate members of the cluster if the current member is too busy to process the request in a timely fashion. WebSphere will route concurrent requests from a user to the same application server to maintain session state.
 
Work load management and clustering


Clustering application servers that host Web containers automatically enables plug-in workload management for the application servers and the servlets they host. Routing of servlet requests occurs between the Web server plug-in and the clustered

application servers using HTTP or HTTPS

This routing is based on weights associated with the cluster members. If all cluster members have identical weights, the plug-in sends equal requests to all members of the cluster, assuming no strong affinity configurations. If the weights are scaled in the range from 0 to 20, the plug-in routes requests to those cluster members with the higher weight value more often. No requests are sent to cluster members with a weight of 0 unless no other servers are available.


Weights can be changed dynamically during runtime by the administrator. A guideline formula for determining routing preference is:

% routed to Server1 = weight1 / (weight1+weight2+...+weightn)

Where there are n cluster members in the cluster.

The Web server plug-in temporarily routes around unavailable cluster members
 
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