You can use the HttpSessionRebalanceOff custom property
to disable HTTP session rebalancing.
With WebSphere® Extended
Deployment Version 6.0
or later, HTTP session rebalancing is automatically enabled. You can
use HTTP session rebalancing to reassign existing session affinities
to new servers that become available for processing the given Web
application. See HTTP session rebalancing
for more information.
Use the HttpSessionRebalanceOff custom property if you want to
return your configuration to the old HTTP session behavior, where
session affinities are established with a particular application server
and are not reassigned to any new servers that become available.
You might consider disabling HTTP session rebalancing if your session
sizes are large. If your sessions are large, the cost of moving the
sessions to a new server might be more than the benefit of taking
the workload off of the original server. You can use Performance Monitoring
Infrastructure (PMI) data to make the decision to turn off session
rebalancing. You might see in your PMI data that response time, memory
utilization, and processor utilization increases on specific servers
to transfer the session information. See the WebSphere Application Server Network
Deployment Information Center for more information about analyzing
PMI data and best practices for using HTTP sessions.
If you leave session rebalancing on, as sessions become more evenly
distributed, and memory and processor utilization also become more
evenly distributed across the servers in the cluster. If a cluster
is more balanced, it is easier for WebSphere Extended Deployment to make autonomic decisions.
Perform the following steps to disable HTTP session rebalancing:
- In the administrative console, click Servers > Dynamic clusters
> dynamic_cluster_name > Custom properties > New.
- Type the name as HttpSessionRebalanceOff and set the
value to true.
- Click Apply and save your configuration.
To turn session rebalancing back on, delete the custom property.