Non-database Consensus Leasing Leasing

Whole Server Migration 7-5 Your database must be reliable. The server instances will only be as reliable as the database. For experimental purposes, a regular database will suffice. For a production environment, only high-availability databases are recommended. If the database goes down, all the migratable servers will shut themselves down. Create the leasing table in the database. This is used to store the machine-server associations used to enable server migration. The schema for this table is located in WL_HOME serverdbdbnameleasing.ddl, where dbname is the name of the database vendor. 2. Set up and configure a data source. This data source should point to the database configured in the previous step. For more information on creating a JDBC data source, see Configuring JDBC Data Sources in Configuring and Managing JDBC for Oracle WebLogic Server.

7.3.5 Non-database Consensus Leasing

In Consensus leasing, there is no highly available database required. The cluster leader maintains the leases in-memory. All the servers renew their leases by contacting the cluster leader, however, the leasing table is replicated to other nodes of the cluster to provide failover. The cluster leader is elected by all the running servers in the cluster. A server becomes a cluster leader only when it has received acceptance from the majority of the servers. If the Node Manager reports a server as shutdown, the cluster leader assumes that server to have accepted it as leader when counting the majority. Consensus leasing requires a majority of servers to continue functioning. Any time there is a network partition, the servers in the majority partition will continue to run while those in the minority partition will fail since they cannot contact the cluster leader or elect a new cluster leader since they will not have the majority of servers. If the partition results in an equal division of servers, then the partition that contains the cluster leader will survive while the other one will fail. If automatic server migration is enabled, the servers are required to contact the cluster leader and renew their leases periodically. Servers will shut themselves down if they are unable to renew their leases. The failed servers will then be automatically migrated to the machines in the majority partition. Note: The leasing table should be stored in a highly available database. Migratable servers are only as reliable as the database used to store the leasing table. Note: XA data sources are not supported for server migration. Note: Consensus leasing requires that you use Node Manager to control servers within the cluster. Node Manager should be running on every machine hosting Managed Servers within the cluster. For more information, see Using Node Manager to Control Servers in Node Manager Administrators Guide for Oracle WebLogic Server. 7-6 Using Clusters for Oracle WebLogic Server

7.4 Automatic Whole Server Migration