Startup Process in a Cluster with Migratable Servers

High Availability for WebLogic Server 3-7

3.9.1 Node Managers Role in Whole Server Migration

Server migration requires Node Manager—it must run on each system that hosts, or is intended to host. Node Manager supports server migration in these ways: ■ You must use Node Manager for the initial startup of migratable servers. When you initiate the startup of a Managed Server from the Administration Console, the Administration Server uses Node Manager to start the server instance. You can also invoke Node Manager to start the server instance using the stand-alone Node Manager client; however, the Administration Server must be available so that the Managed Server can obtain its configuration. ■ You must use Node Manager to suspend, shutdown, or force shutdown of migratable servers. ■ Node Manager tries to restart a migratable server with an expired lease on the system where it was running at the time of failure. Node Manager performs the steps in the server migrate process by running customizable shell scripts, provided with WebLogic Server, that start, restart and stop servers; migrate IP addresses; and mount and unmount disks. The scripts are available for Solaris and Linux. – In an automatic migration, the cluster master invokes Node Manager to perform the migration. – In a manual migration, the Administration Server invokes Node Manager to perform the migration.

3.9.2 Server Migration Processes and Communications

The sections that follow describe key processes in a cluster that contains migratable servers: ■ Section 3.9.2.1, Startup Process in a Cluster with Migratable Servers ■ Section 3.9.2.2, Automatic Whole Server Migration Process ■ Section 3.9.2.3, Manual Whole Server Migration Process ■ Section 3.9.2.4, Administration Servers Role in Whole Server Migration ■ Section 3.9.2.5, Migratable Server Behavior in a Cluster ■ Section 3.9.2.6, Node Managers Role in Whole Server Migration ■ Section 3.9.2.7, Cluster Masters Role in Whole Server Migration

3.9.2.1 Startup Process in a Cluster with Migratable Servers

Figure 3–1 illustrates the processing and communications that occur during startup of a cluster that contains migratable servers. The example cluster contains two Managed Servers, both of which are migratable. The Administration Server and the two Managed Servers each run on different machines. A fourth machine is available as a backup—in the event that one of the migratable Note: Migration of a server instance that was not initially started with Node Manager will fail. 3-8 Oracle Fusion Middleware High Availability Guide servers fails. Node Manager is running on the backup machine and on each machine with a running migratable server. Figure 3–1 Startup of Cluster with Migratable Servers These are the key steps that occur during startup of the cluster illustrated in Figure 3–1 : 1. The administrator starts up the cluster. 2. The Administration Server invokes Node Manager on Machines B and C to start Managed Servers 1 and 2, respectively. See Section 3.9.2.4, Administration Servers Role in Whole Server Migration. 3. The Node Manager on each machine starts up the Managed Server that runs there. See Section 3.9.2.6, Node Managers Role in Whole Server Migration. 4. Managed Servers 1 and 2 contact the Administration Server for their configuration. See Section 3.9.2.5, Migratable Server Behavior in a Cluster. High Availability for WebLogic Server 3-9 5. Managed Servers 1 and 2 cache the configuration 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 3.9.2.7, Cluster Masters Role in Whole Server Migration. 7. Managed Server 1 and 2 periodically renew their leases in the lease table, proving their health and liveness.

3.9.2.2 Automatic Whole Server Migration Process