Enable cell affinity
The cell affinity function preserves sessions even in the event of an on demand router (ODR) outage when you configure unbridged, on demand router (ODR) topologies.
The cell affinity function prevents the loss of sessions when there are multiple ODRs within multiple, unbridged cells, and the IBM HTTP Server is configured to forward session traffic, either through load-balancing or failover, to more than one ODR.
- In the console, select System administration > Cell > Custom properties.
- Set the custom cell property odrSessionAffinityEnabled to true. For more information read about custom properties.
- Configure generic server clusters for other ODR cells. For more information, read about defining generic server clusters for remote ODR cells.
- If we are configuring a multi-tiered configuration, the ODRs in one tier must be configured and operate independently from the ODRs in the other tiers. For more information read about configuring cell affinity in a multi-tiered environment. Note that we can optionally perform this step in a single-tiered environment if you simply want to use a cookie name other than ODRSESSIONID.
- Generate a plugin-cfg.xml.
- Merge the plugin-cfg.xml files into one plugin-cfg.xml file. For more information, read about the pluginmerge.bat or pluginmerge.sh script.
- Install the new plugin-cfg.xml file on the IBM HTTP server. For more information on how to install a new plugin-cfg.xml file, read about configuring an ODR to dynamically update the web server plug-in configuration.
- (dist)(zos) Cell affinity function
Using the cell affinity function, we can configure unbridged, on demand router (ODR) topologies to preserve sessions even in the event of on demand router (ODR) outages. With this function, we can configure the topology in such a way that, when an ODR receives misrouted in-session traffic, the ODR reroutes the traffic back to a working ODR in the original cell. Thus, we can configure an IBM HTTP Server to route to ODRs in multiple cells and still preserve session affinity.
- (dist)(zos) Use generic server clusters with cell affinity
As part of the cell affinity function, in order for the on demand router (ODR) to route to other cells, generic server clusters must be defined to represent those cells. Defining generic server clusters allows each ODR to recognize servers in remote cells.
- (dist)(zos) Configure cell affinity in a multi-tiered environment
We can configure the network to contain multiple tiers of on demand routers (ODRs). In multi-tiered environments, configure the ODRs to have unique ODRSESSIONIDs for the different tiers.
- (dist)(zos) Configure the multi-cluster routing policy
To configure the on demand router (ODR) to route requests to a generic server cluster, configure a multi-cluster routing policy (MCRP) on each ODR. This allows the ODRs in one cell to send requests to a remote cell if no application servers are available in the local cell.
- (dist)(zos) Generating a plugin-cfg.xml
In an environment with an IBM HTTP server routing requests to an on demand router (ODR), the plugin-cfg.xml configuration file ensures that requests are forwarded to the appropriate target servers.
- (dist)(zos) pluginMerge script
Use the pluginMerge script to merge the plugin-cfg.xml files from two or more unbridged cells in order to allow an IBM HTTP server plug-in to route to all cells according to the defined mode.
- (dist)(zos) Cell affinity when an ODR fails
The cell affinity function allows you to configure unbridged, multi-cell, on demand router (ODR) topologies that preserve sessions even in the event of ODR outages.
Intelligent Management: custom properties Cell affinity function
Use generic server clusters with cell affinity Create ODRs Configure an ODR to dynamically update the web server plug-in configuration Generating a plugin-cfg.xml Configure cell affinity in a multi-tiered environment Configure ODRs