7-4 Using Clusters for Oracle WebLogic Server
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Non-database consensus leasing—This version of leasing stores the leasing information in-memory within a cluster member. This version of leasing requires
that all servers in the cluster are started by Node Manager. For more information, see
Section 7.3.5, Non-database Consensus Leasing. Within a WebLogic Server installation, you can use only one type of leasing. Although
it is possible to implement multiple features that use leasing within your environment, each must use the same kind of leasing.
When switching from one leasing type to another, you must restart the entire cluster, not just the Administration Server. Changing the leasing type cannot be done
dynamically.
7.3.3 Determining Which Type of Leasing To Use
The following considerations will help you determine which type of leasing is appropriate for your WebLogic Server environment:
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High-availability database leasing Database leasing basis is useful in environments that are already invested in a
high-availability database, like Oracle RAC, for features like JMS store recovery. The high-availability database instance can also be configured to support leasing
with minimal additional configuration. This is particularly useful if Node Manager is not running in the system.
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Non-database consensus leasing This type of leasing provides a leasing basis option consensus that does not
require the use of a high-availability database. This has a direct benefit in automatic whole server migration. Without the high-availability database
requirement, consensus leasing requires less configuration to enable automatic server migration.
Consensus leasing basis requires Node Manager to be configured and running. Automatic whole server migration also requires the Node Manager for IP
migration and server restart on another machine. Hence, consensus leasing works well since it does not impose additional requirements, but instead takes away an
expensive one.
7.3.4 High-availability Database Leasing
In this version of leasing, lease information is maintained within a table in a high-availability database. A high-availability database is required to ensure that the
leasing information is always available to the servers. Each member of the cluster must be able to connect to the database in order to access leasing information, update and
renew their leases. Servers will fail if the database becomes unavailable and they are not able to renew their leases.
This method of leasing is useful for customers who already have a high-availability database within their clustered environment. This method allows you to use leasing
functionality without being required to use Node Manager to manage servers within your environment.
The following procedures outline the steps required to configure your database for leasing.
1.
Configure the database for server migration. The database stores leasing information that is used to determine whether or not a server is running or needs
to be migrated.
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
