Configuring memory-to-memory replication for the client/server mode

You can use the client/server configuration to attain session affinity using a combination of servers that are configured as client only and server only.

1. Create an application cluster.
   This cluster is used to deploy the application.
   1. Go to the Server Cluster page. Click Servers > Clusters.
   2. Click New.
   3. Type a cluster name for this application cluster.
   4. Click Next.
   5. Define each cluster member server. Type a cluster member name.
   6. Click Apply.
      Complete steps e and f for each server created in this cluster.
   7. Click Next and review the summary of changes.
   8. Click Finish to complete the configuration.
   Do not create a replication domain for the application cluster.
   You have now created a cluster that contains the deployed application.
2. Create a cluster of session manager replication servers that you want to use as the backup cluster.
   1. Go to the Server Cluster page. Click Servers > Server Types > Clusters > Clusters.
   2. Click New.
   3. Type a cluster name for the cluster of session manager replication servers.
   4. Define a replication domain. Select the Configure HTTP session memory-to-memory replication check box.
   5. Click Next.
   6. Define each cluster member server. Type a cluster member name.
   7. Click Apply.
      Complete steps f through g for each server created in this cluster.
   8. Click Next and review the summary of changes.
   9. Click Finish to complete the configuration.
   This step creates a cluster of backup session manager replication servers and associates a replication domain with that cluster.
3. Enable memory-to-memory session replication for each cluster member server in the application cluster.
   1. Go to the appropriate level of session management for the web container level. Click Servers > Server Types > WebSphere application servers > server_name > Web Container Settings > Web container > Session management
   2. Click Distributed environment settings under Additional Properties.
   3. Click Memory-to-memory replication.
   4. Select the Replication domain that you want to use for the replication of sessions.
   5. Select the Client only Replication mode.
      You must configure all session managers connected to a replication domain to have the same topology. If one session manager instance in a domain is configured to use the client/server topology, then the rest of the session manager instances in that domain must be a combination of servers configured as Client only and Server only. If one session manager instance is configured to use the peer-to-peer topology, then all session manager instances must be configured as Both client and server. Alternatively, if one DRS Instance is configured in the client only mode then all DRS Instances in the domain must be configured in either the client only or the server only modes.
   6. Click OK on the Memory-to-memory replication page.
   7. Optional: If you want to change the tuning parameters, click Custom tuning parameters. Click OK. Click Save.
      Note: Using the default tuning parameter custom settings, which specifies time based write interval of 10 seconds, may result in data loss when an application server in your cluster fails. However, this is just a small opportunity for lost data when compared to the significant improvement in performance.
   8. Click OK the Distributed environment settings page.
   9. Click OK the Session management page.
   10. Repeat a through i for each server.
4. Enable memory-to-memory session replication for each cluster member server in the replication cluster.
   1. Go to the appropriate level of session management for the web container level. Click Servers > Application Servers > server_name > Container Settings > Web Container Settings > Session management
   2. Click Distributed Environment Settings under Additional Properties.
   3. Click Memory-to-memory replication.
   4. Select the Replication domain that you want to use for the replication of sessions.
   5. Select the Server only Replication mode.
      You must configure all session managers connected to a replication domain to have the same topology. If one session manager instance in a domain is configured to use the client/server topology, then the rest of the session manager instances in that domain must be a combination of servers configured as Client only and Server only. If one session manager instance is configured to use the peer-to-peer topology, then all session manager instances must be configured as Both client and server. Alternatively, if one DRS Instance is configured in the client only mode then all DRS Instances in the domain must be configured in either the client only or the server only modes.
   6. Click OK on the Memory-to-memory replication page.
   7. Optional: If you want to change the tuning parameters, click Custom tuning parameters. Click OK. Click Save.
      Note: Using the default tuning parameter custom settings, which specifies time based write interval of 10 seconds, may result in data loss when an application server in your cluster fails. However, this is just a small opportunity for lost data when compared to the significant improvement in performance.
   8. Click OK the Distributed environment settings page.
   9. Click OK the Session management page.
   10. Repeat a through i for each server.