Automatic Whole Server Migration Process

Whole Server Migration 7-11 4. Managed Servers 1 and 2 contact the Administration Server for their configuration. See Section 7.4.4.5, Migratable Server Behavior in a Cluster. 5. Managed Servers 1 and 2 cache the configuration with which they started up. 6. Managed Servers 1 and 2 each obtain a migratable server lease in the lease table. Because Managed Server 1 starts up first, it also obtains a cluster master lease. See Section 7.4.4.7, Cluster Master Role in Whole Server Migration. 7. Managed Server 1 and 2 periodically renew their leases in the lease table, proving their health and liveness.

7.4.4.2 Automatic Whole Server Migration Process

Figure 7–2 illustrates the automatic migration process after the failure of the machine hosting Managed Server 2. Figure 7–2 Automatic Migration of a Failed Server

1. Machine C, which hosts Managed Server 2, fails.

7-12 Using Clusters for Oracle WebLogic Server 2. Upon its next periodic review of the lease table, the cluster master detects that Managed Server 2s lease has expired. See Section 7.4.4.7, Cluster Master Role in Whole Server Migration. 3. The cluster master tries to contact Node Manager on Machine C to restart Managed Server 2, but fails, because Machine C is unreachable. 4. The cluster master contacts Node Manager on Machine D, which is configured as an available host for migratable servers in the cluster. 5. Node Manager on Machine D starts Managed Server 2. See Section 7.4.4.6, Node Manager Role in Whole Server Migration. 6. Managed Server 2 starts up and contacts the Administration Server to obtain its configuration. 7. Managed Server 2 caches the configuration with which it started up. 8. Managed Server 2 obtains a migratable server lease. During migration, the clients of the Managed Server that is migrating may experience a brief interruption in service; it may be necessary to reconnect. On Solaris and Linux operating systems, this can be done using the ifconfig command. The clients of a migrated server do not need to know the particular machine to which it has migrated. When a machine that previously hosted a server instance that was migrated becomes available again, the reversal of the migration process—migrating the server instance back to its original host machine—is known as failback. WebLogic Server does not automate the process of failback. An administrator can accomplish failback by manually restoring the server instance to its original host. The general procedures for restoring a server to its original host are as follows: ■ Gracefully shutdown the new instance of the server ■ After you have restarted the failed machine, restart Node Manager and the Managed Server. The exact procedures you will follow depend on your server and network environment.

7.4.4.3 Manual Whole Server Migration Process