41.How many WebLogic servers can be held inside a multi-processor machine?

There is no limitation for the number of servers.

42.What is application tuning?

This process involves ejb pool – size cache and jsp recompilation.

43.What is OS tuning?

This is the process of setting up TCP/IP parameters.

44.What is Core Server tuning?

This is the process involving the tuning of work manager, chuck size, performance packs, chunk pool size and connection backlog buffering.

45.What is JVM tuning?

This process involves monitoring of the garbage collection and the tuning of gc strategy.

46.What is a Machine?

Machine is the logical representation that of the physical machine.

47.What is Node Manager?

Node manager is a service from Java that is capable of running separate process other than that of WebLogic server.

48.What is a domain?

Domain can be defined as the group which comprises of various WebLogic – server resources.

49.How do I increase WebLogic Server memory?

Increase the allocation of Java heap memory for WebLogic Server. (Set the minimum and the maximum to the same size.) Start WebLogic Server with the -ms32m option to increase the allocation, as in this example:
$ java … -ms32m -mx32m …
This allocates 32 megabytes of Java heap memory to WebLogic Server, which improves performance and allows WebLogic Server to handle more simultaneous connections. You can increase this value if necessary.

50.Can I start a Managed Server if the Administration Server is unavailable?

By default, if a Managed Server is unable to connect to the specified Administration Server during startup, it can retrieve its configuration by reading a configuration file and other files directly. You cannot change the server's configuration until the Administration Server is available. A Managed Server that starts in this way is running in Maindex index managed Server Independence mode.

51.How are notifications made when a server is added to a cluster?

The WebLogic Server cluster broadcasts the availability of a new server instance each time a new instance joins the cluster. Cluster-aware stubs also periodically update their list of available server instances.

52.What happens when a failure occurs and the stub cannot connect to a WebLogic Server instance?

When the failure occurs, the stub removes the failed server instance from its list. If there are no servers left in its list, the stub uses DNS again to find a running server and obtain a current list of running instances. Also, the stub periodically refreshes its list of available server instances in the cluster; this allows the stub to take advantage of new servers as they are added to the cluster.

53.How do I use multibyte character sets with WebLogic jDriver for Informix?

Currently, multibyte character sets are not supported for the WebLogic jDriver for Informix driver.

54.Can I configure the messaging bridge to automatically downgrade the quality of service if the Exactly-once service isn't available on either the source or target bridge destination?

Yes, just make sure to select the QOS Degradation Allowed check box on the Messaging Bridge > Configuration > General administration console page.

55.What can be the various reasons for a server crash?

• Native IO
• SSL Native Libraries
• JVM
• Supported Configuration
• JDBC Driver issue

56.How do you troubleshoot a crash?

JVM crash generates a hs_err_pid file. We need to look into the stack trace of the hs_err_pid file .
If the thread is from a native io, we need to disable native io.
if the stack trace is from the driver, we need to get in touch with the drive team.
Quite possibly its a problem with driver. Changing the type of driver can be a workaround.
If the thread shows it coming from an optimzed code, we can turn of optimization.
If the stack is from native calls of application, its a bug with the application and it has to b modified.

57.Ho do you troubleshoot Server Hang?

We can use java weblogic.Admin PING to check if we get a normal response.
We need to take multiple thread dumps with kill -3 pid on unix and CTLR Break on Windows.
Analyze the thread dump to find the root cause.

58. What are the various causes for OUT OF MEMORY?

• Insufficient heap size, not able to match the extra load.
• Objects licing too long, like HTTP Sessions.
• Memory leak in application code.
• Full GC not happening due to JVM Bug.

59.How to troubleshoot and overcome such issues?

Gather memory data by enabling GC verbose.
If its due to Http Session, timing out http session after certain interval might help.
Look into the code for jdbc connection handling.
Optimizing the heap size according to the load.

60.How to troubleshoot it?

In Solaris environment, we need to take pstack and prstack and see what the threads are doing.
In Windows we need to use pslist and process explorer.