Startup Process in a Cluster with Migratable Servers
7.4.3 Using High Availability Storage for State Data
The server migration process migrates services, but not the state information associated with work in process at the time of failure. To ensure high availability, it is critical that such state information remains available to the server instance and the services it hosts after migration. Otherwise, data about the work in process at the time of failure may be lost. State information maintained by a migratable server, such as the data contained in transaction logs, should be stored in a shared storage system that is accessible to any potential machine to which a failed migratable server might be migrated. For highest reliability, use a shared storage solution that is itself highly available—for example, a storage area network SAN. In addition, if you are using a database to store leasing information, the lease table, described in the following sections, which is used to track the health and liveness of migratable servers, should also be stored in a high availability database. For more information, see Section 7.3, Leasing.7.4.4 Server Migration Processes and Communications
The sections that follow describe key processes in a cluster that contains migratable servers: ■ Section 7.4.4.1, Startup Process in a Cluster with Migratable Servers ■ Section 7.4.4.2, Automatic Whole Server Migration Process ■ Section 7.4.4.3, Manual Whole Server Migration Process7.4.4.1 Startup Process in a Cluster with Migratable Servers
Figure 7–1 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 servers fails. Node Manager is running on the backup machine and on each machine with a running migratable server. Note: You should ensure that your login scripts .cshrc, .profile, .login, and such only echo messages from your shell profile if the shell is interactive. WebLogic Server uses an ssh command to login and echo the contents of the server.state file. Only the first line of this output is used to determine the server state. 7-10 Using Clusters for Oracle WebLogic Server Figure 7–1 Startup of Cluster with Migratable Servers These are the key steps that occur during startup of the cluster illustrated in Figure 7–1 : 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 7.4.4.4, Administration Server Role in Whole Server Migration. 3. The Node Manager on each machine starts up the Managed Server that runs there. See Section 7.4.4.6, Node Manager Role in Whole Server Migration. 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
Parts
» Oracle Fusion Middleware Online Documentation Library
» Document Scope and Audience Guide to this Document
» What Are the Benefits of Clustering? What Are the Key Capabilities of a Cluster?
» Servlets and JSPs EJBs and RMI Objects
» Getting Connections with Clustered JDBC Failover and Load Balancing for JDBC Connections
» Pure-Java Versus Native Socket Reader Implementations
» Client Communication via Sockets
» How WebLogic Server Creates the Cluster-Wide JNDI Tree
» How WebLogic Server Updates the JNDI Tree Client Interaction with the Cluster-Wide JNDI Tree
» Load Balancer Configuration Requirements Load Balancers and the WebLogic Session Cookie
» Related Programming Considerations How Session Connection and Failover Works with a Load Balancer
» Round-Robin Load Balancing Weight-Based Load Balancing
» Transactional Collocation Optimization for Collocated Objects
» Methods of Configuring Clusters Load Balancing for JDBC Connections
» Using Replication Groups HTTP Session State Replication
» Connection with Load Balancing Hardware Failover with Load Balancing Hardware
» Configuration Requirements for Cross-Cluster Replication
» Configuring Session State Replication Across Clusters
» Clustering Objects with Replica-Aware Stubs
» Failover and JDBC Connections Understanding Server and Service Migration
» Migration Terminology Oracle Fusion Middleware Online Documentation Library
» Features That Use Leasing Leasing Versions
» Determining Which Type of Leasing To Use High-availability Database Leasing
» Non-database Consensus Leasing Leasing
» Preparing for Automatic Whole Server Migration
» Configuring Automatic Whole Server Migration
» Startup Process in a Cluster with Migratable Servers
» Automatic Whole Server Migration Process
» Manual Whole Server Migration Process Administration Server Role in Whole Server Migration
» Migratable Server Behavior in a Cluster Node Manager Role in Whole Server Migration
» Cluster Master Role in Whole Server Migration
» JMS-related Services JTA Transaction Recovery Service
» Custom Store Availability for JMS Services Default File Store Availability for JTA
» Best Practices for Targeting JMS when Configuring Automatic Service Migration
» Architecture Web Application Tiers
» Combined Tier Architecture De-Militarized Zone DMZ Load Balancer Proxy Plug-In
» No Collocation Optimization Firewall Restrictions
» Multi-Tier Proxy Architecture Proxy Architecture Benefits Proxy Architecture Limitations
» Proxy Plug-In Versus Load Balancer
» DMZ with Two Firewall Configuration
» Dynamic Cluster Address If you do not explicitly define a cluster address
» Configuration Roadmap Install WebLogic Server
» Starting a WebLogic Server Cluster
» Configure Node Manager Configure Load Balancing Method for EJBs and RMIs
» Sample web.xml This section contains a sample deployment descriptor file
» Accessing Applications Via the Proxy Server Ensure that applications clients will
» Configure Replication Groups Configure Migratable Targets for Pinned Services
» Migrating When the Currently Active Host is Unavailable Use this migration
» Configure Multicast Time-To-Live TTL Configure Multicast Buffer Size
» Cluster-Related Configuration Options Follow Usage and Configuration Guidelines
» Manual Migration of the JTA Transaction Recovery Service State Management in a Cluster
» Naming Considerations Administration Server Considerations
» Firewall Considerations Avoiding Problems
» Check the Server Version Numbers Check the Multicast Address Check the CLASSPATH Value
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