BEA WebLogic Server Tuning Guide

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All WebLogic Server instances of one WebLogic Server cluster (and only those instances) should use the same key.
It can be set to the WebLogic Server cluster name itself, but is subject to Guardian filename rules (8-character
maximum length, with the first character an alphabetical character).
The following command sets the filter key to cluster1:
$ add_define =PTCPIP^FILTER^KEY class=map file=cluster1
When nodemanager is used, these defines need to specified in the shell script that starts the nodemanager.
3.13 Configuring the Listen Address for WebLogic Server
The WebLogic Server stores the ClusterAddress and expects to reach a surviving member of a cluster for
implementing failover for Entity beans and EJB Handles. Therefore, the following guidelines are recommended:
• Configure each instance of the WebLogic Server in a cluster to listen on different IP addresses but use a
common port. This is the recommended configuration. According to the WebLogic Server documentation,
failure to adhere to this recommendation means that entity bean failover and EJB handle failover will not
work. Moreover, the non-DNS form of cluster addresses (where the cluster address is specified as a list of
IP:port values) is recommended only for development use by BEA.
• Set up a DNS name that maps to all the IP addresses used by instances that are part of a WebLogic Server
cluster.
• This DNS name should not map to any other IP address not used by the cluster members.
For example, if a cluster is set up with four member instances:
• Configure a single common port as the listen port for all the 4 servers in the cluster.
• Configure each server instance with its own IP address.
• Set up a DNS name that maps to these 4 IP addresses only. Note: this DNS name is specified in the
WebLogic Server configuration as the ClusterAddress for a particular Cluster.
While it might look daunting that large clusters require many more addresses if we go with one IP address per
instance, the mitigating factor is that the TCP/IP V6 stack lets Alias IP addresses be specified. This lets more IP
addresses be configured on a NonStop server instead of configuring multiple LAN adapters.
Also, as noted above, the requirement to use the same port number (and a different IP address) in every instance of
a cluster is a requirement for those applications that need entity bean and EJB handle failover capabilities. For
applications that do not use it, the cluster can be configured with the same IP address for all the server instances,
but different port numbers.
3.14 Memory Considerations: Moving QIO to KSEG2
WebLogic Server applications are typically configured with large Java heap sizes, in excess of 128 MB or 256MB.
In addition, the JVM and native components (for example, JDBC/MX and the SQL/MX CLI) allocate memory for
their own use. Therefore, the overall heap space required in a WebLogic Server instance might be considerably
larger than the Java heap space alone.
When a process uses the TCP/IP V6 stack transport provider for socket operations (for example, the JVM running
the WebLogic Server), it becomes a QIO client. NonStop server QIO shared-memory segments are designed such
that when a QIO client process makes a socket request, a portion of the process address space is reserved for the
QIO segment. This limits the maximum useable heap size for the JVM running WebLogic Server.