This OBE tutorial is designed to get you started
with new cluster of WebLogic Servers. After starting the servers, you
use their logs as well as the administration console to confirm
that each joined the cluster successfully. Additional OBE tutorials extends this cluster's capabilities to support load balancing and
failover of JavaEE applications.
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Overview
A WebLogic Server cluster consists of multiple
WebLogic Server instances, running simultaneously and working together
to provide increased scalability and reliability. A domain includes one
or more WebLogic Server instances, which can be clustered,
nonclustered, or a combination of clustered and nonclustered
instances. A domain can include multiple clusters.
A cluster appears to clients as one WebLogic Server
instance. The server instances that constitute a cluster can run on one
machine or on different machines. You can increase a cluster’s capacity
by adding server instances to the cluster on an existing machine, or by
adding machines to the cluster to host the incremental server instances.
All server instances in a cluster use multicast or
unicast to broadcast regular server heartbeat messages to other members
of the cluster. Each heartbeat message contains data that uniquely
identifies the server that sends the message. Servers broadcast their
heartbeat messages at regular intervals. In turn, each server in a
cluster monitors the multicast or unicast address to ensure that all
peer servers’ heartbeat messages are being sent.
If any of your managed servers are
running, shut them down. For example, using the administration console,
select Environment > Servers
from the Domain Structure panel. Then click the Control tab.
2.
Select the check box for each managed server. Click the Shutdown button and select Force Shutdown Now.
3.
Click Lock & Edit
in the Change Center panel of the administration console. Select Environment
> Clusters from the Domain Structure panel. Click the New button.
4.
Enter the following:
Field
Value
Name
dizzyworldCluster
Messaging Mode
Multicast
Multicast Address
(use default)
Multicast
Port
(use default)
Click the OK button.
Tip: For multicast communication to function
properly, your machine's network interface must be active.
5.
Select the new cluster. Click the Configuration > Servers tab.
6.
Click the Add button.
7.
Select one of your managed servers and click Finish.
8.
Repeat the previous steps to add
the remaining two managed servers to the cluster.
9.
In the Change Center panel,
click Activate Changes.
Start one of your managed servers.
From a shell, change directories to <domain>\bin
and use the startManagedServer
script. For example:
>./startManagedWebLogic.sh
dizzy1 localhost:7001
Supply your administrative
credentials, if prompted.
2.
Watch the server start up using the shell's standard
output stream. At some
point, you should see it begin listening for cluster communication and
begin waiting to synchronize with other servers in the cluster. Because the
other servers have not started, there is nothing for it to
synchronize with yet:
<Jul 24, 2008 1:59:01 PM EDT> <Notice>
<Cluster> <BEA-000138> <Listening for announcements from
cluster dizzyworldCluster on 239.192.0.0:7001.>
<Jul 24, 2008 1:59:01 PM EDT> <Notice> <Cluster>
<BEA-000133> <Waiting to synchronize with other running
members of dizzyworldCluster.>
. . .
<Jul 24, 2008 1:59:35 PM EDT> <Notice> <Cluster>
<BEA-000102> <Joining cluster dizzyworldCluster on
239.192.0.0:7001>
Tip: If your managed server's Standard Out
Severity Level is not set to Notice or lower, these log messages
will not be shown in the shell. Alternatively, use the console to view
the contents of the server's log file.
3.
Repeat the previous steps to start the other two managed servers.
Once again, use the shell's standard output stream or the server log to confirm that the
servers joined the cluster successfully:
<Jul 24, 2008 8:50:38 PM EDT> <Info>
<Cluster> <BEA-000111> <Adding dizzy2 with ID
-1782128580192434823S:172.16.205.130:[7005,7005,-1,-1,-1,-1,-1]:dizzyworld:dizzy2
to cluster: dizzyworldCluster view.>
<Jul 24, 2008 8:50:38 PM EDT> <Info> <Cluster>
<BEA-000111> <Adding dizzy1 with ID
-6563747670768289324S:172.16.205.130:[7003,7003,-1,-1,-1,-1,-1]:dizzyworld:dizzy1
to cluster: dizzyworldCluster view.>
Tip: If your managed server's Standard Out
Severity Level is not set to Info or lower, these log messages
will not be shown in the shell. Alternatively, use the console to view
the contents of the server's log file.
Return to the administration console. Select Environment > Clusters
from the Domain Structure panel. Then select your cluster.
2.
Click the Monitoring tab.
3.
The resulting table should indicate that all the three managed servers
are currently participating in the cluster. Various communication
statistics are also available.
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