Using SNAplus2 in a High Availability Environment

Using SNAplus2 with MC/ServiceGuard

Step 1. List all of the mission critical applications that use SNAplus2 for SNA network connectivity.

Step 2. Diagram your network topology so that you know the location of the servers that are part of the ServiceGuard cluster and any other systems needed for SNA network connectivity.

Step 3. List the SNAplus2 LSs that must be highly available. The SNAplus2 LSs are what will be monitored by ServiceGuard to determine if the HP 9000 server is providing SNA network connectivity. If all of the highly available SNAplus2 LSs are active, the server is providing SNA network connectivity.

Step 4. Identify a primary server and one or more backup servers for the SNAplus2 package. When the primary server fails to provide SNA network connectivity (that is, the SNAplus2 LS is no longer active), ServiceGuard will automatically migrate the package to another server system.

Note that to simplify the package migration during failure episodes, we recommend that you run only one SNAplus2 package in your ServiceGuard cluster; that is, at any one time, only one system in a ServiceGuard cluster will be running a highly available SNAplus2 LS. Backup systems in your cluster can provide SNAplus2 services for non-mission critical applications.

Step 5. Define how the mission critical applications will be impacted by the migration from one server to another. Since LU-LU sessions will be lost, specify what you will be required to do to re-activate an LU-LU session through another server system. If an application needs to be restarted after a server system failure (perhaps because the application runs on the server), determine if you want ServiceGuard to automate the application startup.

Step 6. Create a set of commands that ServiceGuard will issue when an SNAplus2 LS fails so that the migration to a backup server happens smoothly. Make sure this set of commands contain halt commands to free SNAplus2 resources on the primary server and run commands to activate the necessary resources on the backup server.

Figure D-4, “SNAplus2 on Primary and Backup Servers,” (shown previously) illustrates these steps. The picture shows the network topology including the SNAplus2 servers and clients. The mission critical applications are APPC TPs. The SNAplus2 LS that is highly available is HALS. The primary server is hp_pri and the backup server is ha_back.

Appendix D

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