Technical data

2 Overview of WebLogic Server Domains
2-4 Configuring and Managing WebLogic Server
For more information about the Administration Server and its role in the WebLogic
Server JMX management system, see “System Administration Tools” in the
Administration Guide.
What Happens if the Administration Server Fails?
The failure of an Administration Server for a domain does not affect the operation of
Managed Servers in the domain. If an Administration Server for a domain becomes
unavailable while the server instances it manages—clustered or otherwise—are up and
running, those Managed Servers continue to run. If the domain contains clustered
server instances, the load balancing and failover capabilities supported by the domain
configuration remain available, even if the Administration Server fails.
If an Administration Server fails because of a hardware or software failure on its host
machine, other server instances on the same machine may be similarly affected.
However, the failure of an Administration Server itself does not interrupt the operation
of Managed Servers in the domain.
For more information, see “Recovering Failed Servers” on page 10-1.
Managed Servers and Clustered Managed Servers
In a domain, server instances other than the Administration Server are referred to as
Managed Servers. Managed Servers host the components and associated resources that
constitute your applications—for example, JSPs and EJBs. When a Managed Server
starts up, it connects to the domain’s Administration Server to obtain configuration and
deployment settings.
Note: Managed Servers in a domain can start up independently of the Administration
Server if the Administration Server is unavailable. See “Recovering Failed
Servers” on page 10-1 for more information.
Two or more Managed Servers can be configured as a WebLogic Server cluster to
increase application scalability and availability. In a WebLogic Server cluster, most
resources and services are deployed to each Managed Server (as opposed to a single
Managed Server,) enabling failover and load balancing. To learn which component
types and services can be clustered—deployed to all server instances in a cluster—see
“What Types of Objects Can Be Clustered?” in Using WebLogic Server Clusters.