WAS INTERVIEW PART-2 QUESTIONS AND ANSWERS

          WAS INTERVIEW PART-2 QUESTIONS AND ANSWERS


1) what are the different components in Wily Introscope ?

A)      1) Collector
          2) MOM (Manager of Managers)
          3) Webview (thin client)
         4)  Console (Thick Client)



2)    In which log file garbage collector information will be recorded ? how to enable garbage collector ?

A)  ----> Nativestdout.log Nativestderr.log are GC logs 

    ---> get into the admin console ->applicationserver->select JVM->Java & Process Management->process definition-> Java Virtual Machine.

There u will have an option to enable GC logging.




3)   How can we check the performance of the application server without external monitoring tools?



A)  Through Websphere in build monitoring tool called Tivoli Performance Monitoring under Monitoring and tuning in Admin Console.
                              (or) 

Tivoli Performance Viewer (TPV): It enables the administrators and programmers to monitor the overall health of the WebSphere Application Server without leaving the Admin console.
From TPV, you can view current activity or log Performace Monitoring Infrastructure(PMI) for the following:
- System resources such as CPU utilization.
- WebSphere pools and queues such as DB connection pool.
- Customer Application data such as servlet response time.

4) How many plugins are required by http server ?

A) ONLY ONE 

5)  what is a collector tool ?

A)  ----> Collector is a tool which provides all log files. These log files contains failure info. 
      ----> If the bugs cant be cleared by administrator, then by using this tool we will send all log files to IBM people.

6)  How many JVMs will there for each server ?

A) ----> It depends on the enironment. There can be any number no limit.
    ----> Generally in Producation a JVM is put in two servers clustered horizontally to avoid single point of failure (SPOF)

7) what is Embedded HTTP Server ?

A) ----> The embedded HTTP Server receives requests for WebSphere assets from the WebSphere plug-in and passes them to an application server for processing.

   ---->   Any response from the application server is passed back to the WebSphere plug-in for display.

 ----->   The embedded HTTP server supports both HTTP and secure HTTP (HTTPS) protocols for connecting Web servers to application servers.
----> By default, the embedded HTTP server listens for requests on TCP/IP port 9080 but this is configurable.

For example: http://server-name:9080/servlet

You can also use the embedded HTTP server to test your WebSphere applications, but it should never be used as a production Web server.


8)   How to know whether the plug-in ic propagated or not ?

A) Check the plugin-cfg.xml file in webserver


9) what are the different types of log files we have ? what is the use of each log file ?

A)  1)  SystemOut.log :  standard JVM output log
          ---> Indicates if the code running on the Application Server started and stopped successfully. 
          --->Destination and name are configurable. 
         ----> Can be used for user messages. 
2)      SystemErr.log : standard JVM error log 
         ----> Identifies exceptions thrown by the code running on the Application Server. 
         ----> Destination and name are configurable. 
3)     startServer.log and stopServer.log :
         ----> Describes the startup and shutdown of the Application Servers. 
4)  Activity.log: events that show a history of activities 
         ----> Use Log Analyzer to read output from this file. 
          
5)  http_plugin.log : plug-in trace log 
       ----> Errors and data from the Web server plug-in. 
6) trace.log :  output from diagnostic trace. 
       ----> Destination and name are configurable. 
       ----> All WebSphere Application Server log files are under the logs directory. where is the WebSphere Application Server installation directory (for Windows 2000 the default is: C:Program FilesWebSphereAppServer). 

----> SystemOut.log and SystemErr.log are the default names for the JVM logs. They contain server and user program information (sent by: System.out.xxx code in the program). The default location is logs. 

----> startServer.log and stopServer.log can also be found under the logs directory. These files contain information logged by the server as it starts up and shuts down. 

-----> The activity.log file contains information about normal events that are occurring to the system. For example, when a module is first accessed and loaded into the server container, or when a JSP is compiled, or when requests are directed from the HTTP server to the Application Server. Activities such as these are time stamped and recorded in the activity.log file. The activity.log file size can be set. 

-----> The default value is 1024K, or 1 megabyte. The minimum size is 8K and maximum is 1048576K (1 gigabyte). To do this, set the com.ibm.ws.ras.ActivityLogSize value in the logging.properties file in the properties directory.

10)   what are the parameters available in IHS servers response file ?

A) ---->   # In real life, you must concatenate these

   -----> # parameters onto one continuous line. They

----- ># may NOT be split as we do here

-----> -W maintenance.package=

-----> "/fixPaks/7.0.0-WS-IHS-LinuxX32-FP0000011.pak;"

----> -W product.location="/IBM/WebSphere/HTTPServer"

----> -OPT checkFilePermissions="true"

----> -OPT disableNonBlockingPrereqChecking="true"

----> -W update.type="install"

11)  How to deploy web/jar files in Weblogic or tomcat in unix/Linux environment ?

A)  In weblogic 9.0--> 1)copy the web / Jar Application paste in Auto deployment folder.it's called Hot deployment.

2) Otherwise go to Administrative console--> http://localhost:7001/console --> Deployment->Loc/Edit Click--> Install--> select source path
3) WLST --> Weblogic Scripting tool--> type command Deploy
java.Weblogic.Deployer http://localhost:7001 -user weblogic -password weblogic -deploy application name Managedserver1,Managed server2.



12)    In which log file garbage collector information will be recorded ? how to enable garbage collector ?

A)  ----> Nativestdout.log Nativestderr.log are GC logs 

    ---> get into the admin console ->applicationserver->select JVM->Java & Process Management->process definition-> Java Virtual Machine.

There u will have an option to enable GC logging.

13)   How can we check the performance of the application server without external monitoring tools?

A)  Through Websphere in build monitoring tool called Tivoli Performance Monitoring under Monitoring and tuning in Admin Console.
                              (or) 

Tivoli Performance Viewer (TPV): It enables the administrators and programmers to monitor the overall health of the WebSphere Application Server without leaving the Admin console.
From TPV, you can view current activity or log Performace Monitoring Infrastructure(PMI) for the following:
- System resources such as CPU utilization.
- WebSphere pools and queues such as DB connection pool.
- Customer Application data such as servlet response time.

14)   Can someone explain what it means by Federate A NODE ?

A)   ---> Federation is nothing but addition.

     ----> Federating the node means we have to add the node of the standalone application server to the DMGR profile.

                           (OR)

---->  Federating node means adding stand alone application or stand alone profile to deployment manager(DMGR), we can achieve this by using admin console or addnode command of stand alone profile.

CMD: ./addNode.sh 

----> Once this process is successfully done, one nodeagent server is created for app server, this nodeagent is responsible for communication between dmgr and application server.


15)   Solving OutOfMemoryError in WAS. How to Increase WebSphere JVM Memory with / without using IBM Console?

A)  --->  When I upload a big file through java application running on  Websphere Application Server , I got  OutOfMemoryError   , as given below 

---->   JVMDUMP013I Processed Dump Event "uncaught", detail "java/lang/OutOfMemoryError".  

---->   Also memory leak is  a common memory problem that also leads to OutOfMemory error. In Java ,  memory leaks can not happen as  it has automatic Garbage Collection (GC). GC  removes  unused objects that are not referenced anymore. But if an object is not used, but is still referenced, GC does not remove it, which leads to memory leaks in JVM .

----->  Due to the above memory leak or large objects error ,  the performance of the application server may decline 

----> WAS may be crashed with OutOfMemory error. please check the error  message  java.lang.OutOfMemoryError”  in the WAS  log file ( i.e. native_stderr.log) 

---->  One of Solution to the above error : 

---->   When I increase the JVM Heap Size ,  the problem got solved . Now let us see , how to increase JVM Heap Size in Websphere Application Server

----->  You can solve the problem in two ways 

            i) Using the IBM console 

          ii) By changing  the server.index file directly

---->  i). To tune the JVM Max Heap size using the IBM console  

----->   1. Open the WebSphere Application Server administrative console, 

                http://hostname:port/ibm/console, and log in.

        2. Expand Servers  -> Application servers  -> server1  -> Java and Process Management  -> Process Definition  -> Java Virtual Machine.

         3. Change the Max Heap Size to a larger value.

         4.  Click Apply and click Save .

                     Restart WebSphere Application Server.

-----> ii)  By changing  the server.xml file directly

              Open the server.xml file located in the following directory

/opt/IBM/WebSphere/AppServer/profiles/AppSrv01/config/cells/YourSrverNode01Cell/nodes/YourServerNode01/servers/server1

---->   Then  you have to reduce the  max heap size value using the IInd method ..(i.e. change server.xml file directly)

----> Tuning the max heap size

  Setting the JVM heap size directly relates to the number of server instances need to be  started on a specific node and the total RAM available on that machine. The total value of all server JVM heap sizes on a specific node must be less than half of the total RAM of that computer. To determine the max heap size , you can use the following equation 

max_heap_size  = Total_RAM / 2 / no_of_servers_instance

For example, to support two servers instance  on a machine with 4  GB of RAM:

max_heap_size = 4 GB / 2 / 2

        =2 GB /  2  =  1 GB 

The maximum heap size is 1 GB  for each server instance.

---->  Default maximum heap size is 250 MB

------>  Increasing the minimum heap size & maximum heap size can improve the start-up of application server. The number of garbage collection (GC)  occurrences are reduced and a 10% gain in performance is realized. 

16)  How to determine Max Heap Size is too large or too small  for your application.?  

A)   ---->  If  GC takes a so long time to clean up objects with large heap, you can reduce the maximum heap size. 

     -----> If  GC frequency is too high, the heap may be too small for the application and GC needs to run frequently, so you may increase the maximum heap size.