1)
In a Web-based architecture,
if you try to hit the URL, it shows an error like page cannot be displayed, How
to troubleshoot this issue?
Ans: The Flow of Request happens from
Load Balancer >>
Webserver >> Appserver >> DBso the investigation for such issues
should also follow the same routes .. ( well thats how i follow )
Try to check if the url
is responding from your end. (This will eliminate if its specific to a user or
its error for every one)
Check the Webserver if
its running or not, If it’s not running start it
Check if the
application server and application is running.. if not start it
Try to access the
Application directly from the Appserver .. ie using the http transport port. ie
wc_defalut .. ( this will identify if the error is due to App server or is with
the Webserver/plugin)
check for the errors in
the Appserver and web server logs
Check for the config in
the plugin file to ensure that the url which is being hit is avaliable in the
plugin-xml.cfg ( If it is not then it could be possible that the plugin was not
regeneraed ad propagated after the deployment)
Enable the trace in the
plugin-xml.cfg to understand in the plugin logs whether the plugin is
forwarding the req to the appservers or not
Lastly also check if
the page which you are requesting is avaliable within the web modules.
2)
Suppose in a cluster
environment one of the servers is about to reach 100% CPU utilization,
remaining servers are in normal utilization If this is a scenario then how it
will occur and what is the reason for that case and how to resolve these kind
things?
When i looked at the
System out log , there are lot of threads are in hung state.
Solution:
Take the 3 thread dumps
in interval of 1-2 mins. (Kill -3 PID)
Kill the that process (
kill -9 PID)
Restart the server/JVM
Analyze the dumps.
3)
If client is complaining
that app is slow, then wat is the steps which need to be followed up to resolve
the issue?
Well there are many
reasons for the slow behaviour
Check the CPU
utilisation of the appserver and the entire server to see if there are cpu
bottleneck
Check the Memory
utilisation of the appserver and the entire server to see if there are memory
bottleneck
Check the systemout.log
to check if there are any hung threads or OOM
Check the heap allocated
to the JVM
Check the connection to
the DB , it could be possible that the connections to the DB has got MAXED out
Check the Plugin and
webserver logs to see if its connection to has maxed
Take the thread dump
for further analysis
4)
Suppose we have 10 applications
in our environment? How the request goes to particular application?
A request wills
generally goto an exact application by the context root of that application.
5) What
is the difference between the Generate Plug in and Propagate Plug in?
generate plugin:-if any changes are
done in websphere environment then we have to do generate plugin(changes
like:-change in virtual host, creating or deleting servers or clusters,
deploying or deleting new application)to create the plugin we have a cmd bin/genplugincfg.bat->dmgr/bin
directory) then it will be generated in the DMGR cell level.
Propogate plugin - It transfers the
generated plugin to it respective remote webserver config path :
<WEBSERVER_HOME>/Plugins/config.
6) When
we synchronize node from cmd mode, why do we need to stop node agent. ?
To make sure no changes to the
master configuration while performing full sync via cmd. If node agent Is up
and someone else saving configuration which conflict to the full sync...
if did not stop node agent, then
changes made by sync is not recognize and in next auto sync all these changes
are overridden. because node agent sync is done only from dmgr. so it
identifies only changes known by dmgr, if u do manually sync without stopping
nodeagent ,then dmgr doesn't come to know these changes and those are
overridden in next sync.
7) What
is the difference between deploying an EAR File and WAR File?
·
In ear files no need to give the context
root...in war files u have to give
·
EAR menace Enterprise application and
WAR menace web application
·
In WAR Auto Deployment is possible where
else in EAR auto deployment is not possible
·
WAR contains Web.xml file where EAR
contain web.xml and Application.xml file
8) What
is node group?
A node group is a collection of
managed nodes. Nodes that you organize into a node group need to be similar in
terms of installed software, available resources, and configuration to enable
servers on those nodes to host the same applications as part of a server
cluster
.A default node group called
DefaultNodeGroup is automatically created for you when the deployment manager
is created, based on the deployment manager platform. New nodes on similar
platforms are automatically added to the default group. A node must belong to
at least one node group, but can belong to more than one.
As long as you have nodes in a cell
with similar platforms, you do not need to do anything with node groups. New
nodes are automatically added to the node group. However, before adding a node
on a platform that does not have the same capabilities as the deployment
manager platform, you will need to create the new node group.
9) What is plug-in configuration file?
The web server plug-in
configuration file controls whether an application server or the web server
handles user requests. You must regenerate this global plug-in configuration
file whenever you change the configuration settings for an application server,
cluster, web container transport, or virtual host alias that is contained in
the cell. You must also regenerate this file whenever you add a new application
server, cluster, web container transport, or virtual host alias to the cell.
The global plugin-cfg.xml file is placed in the %was_profile_home%/config/cells
directory. This configuration file includes the URIs for all of the applications
that are deployed in this cell. If your web server is located on a remote
machine, you must manually move this plug-in configuration file to that
machine.
10) What
is Node Agent?
The node agent process serves as an
intermediary between the application servers on the node and the deployment
manager. The node agent process runs on every node and is specialized to
perform node-specific administration functions, such as server process
monitoring, configuration synchronization, file transfer, and request routing.
We can stop node agent , Retstart
nodeagent and restart all servers on node from the console but we can't start from the console if it is
stopped.
11) What
is Deployment manager?
The deployment manager provides a
single, central point of administrative control for all elements of the
distributed cell.
we can stop the deployment manager
from console but can't start if from the console.
12) Difference between Managed node and
Unmanaged node ?
A managed node contains an
application server process that runs within the deployment manager cell. The
managed node is associated with a node agent process that maintains the
configuration for the node and controls its operation. Choosing this option
results in running the add node utility to federate an existing stand-alone
application server.
An unmanaged node represents a node
in the topology that does not have an application server process or a node
agent process. Unmanaged nodes are for other server processes, such as web
servers that exist on their own node in the topology.
13) Can you start node from the console?
no
14) What will happen if you stop the node from console?
It will stop all the process which
are running under the node ( servers & nodeagent).
15) What is Buses
A service integration bus supports
applications using message-based and service-oriented architectures. A bus is a
group of interconnected servers and clusters that have been added as members of
the bus. Applications connect to a bus at one of the messaging engines
associated with its bus members.
16) What is application server?
An application server is a server
that provides services required to run enterprise applications.
17) JMS providers
A JMS provider enables messaging
based on the Java Message Service (JMS). It provides J2EE connection factories
to create connections for JMS destinations.
18) Connection factories
A connection factory is used to
create connections to the associated JMS provider. These connection factories
can be used for accessing JMS Queue and JMS Topic destinations.
•
Queue
connection factories
A queue connection factory is used
to create connections to the associated JMS provider of the JMS queue
destinations, for point-to-point messaging.
19) Topic connection factories
A topic connection factory is used
to create connections to the associated JMS provider of JMS topic destinations,
for publish and subscribe messaging.
20) Queues
A JMS queue is used as a
destination for point-to-point messaging.
21) Topics
A JMS topic is used as a
destination for publish/subscribe messaging.
22) Activation specifications
A JMS activation specification is
associated with one or more message-driven beans and provides configuration
necessary for them to receive messages.
23) What are the differences between Queue and
Topic ?
Queue:
•Point-to-point model
•Only one consumer gets the message
•Messages have to be delivered in
the order sent
•A JMS queue only guarantees that
each message is processed only once.
•The Queue knows who the consumer
or the JMS client is. The destination is known.
•The JMS client (the consumer) does
not have to be active or connected to
the queue all the time to receive or read the message.
•Every message successfully
processed is acknowledged by the consumer.
Topic:
•Publish/subscribe model
•Multiple clients subscribe to the
message
There is no guarantee messages have
to be delivered in the order sent
•There are no guarantees that each
message is processed only once. -- As this can be sensed from the model
•The Topic, have multiple
subscribers and there is a chance that the topic does not know all the
subscribers. The destination is unknown.
•The subscriber / JMS client needs
to the active when the messages are produced by the producer, unless the
subscription was a durable subscription.
•No, Every message successfully
processed is not acknowledged by the consumer/subscriber.
24) What
is the use of garbage collector?
You can check the verboseGC report
to determine:
How much time the JVM is spending
performing garbage collection.
Ideally, you want the JVM to spend
less than 5 percent of its processing time doing garbage collection. To
determine the percentage of time the JVM spends in garbage collection, divide
the time it took to complete the collection by the length of time since the
last AF and multiply the result by 100. For example:
83.29/3724.32 * 100 = 2.236
percentIf you are spending more than 5 percent of your time in garbage
collection and if garbage collection is occurring frequently, you might need to
increase your Java heap size.
Two main technologies used to
remove the garbage:
Mark Sweep Collector and Copy Collector
IBM uses a mark sweep collector (or) a
combination for generational (gencon)
Garbage Collection can be broken down into 3
steps
a) Mark: Find all live objects in the system
b) Sweep: Reclaim objects that are no longer
referenced
c) Compact: Converts many small holes into
fewer large ones to avoid fragmentation
The first thing to notice here is
the “action=” figure. Seven different actions can occur for an allocation
failure:
action=0 means the pinnedFreeList
was exhausted.
action=1 means a preemptive garbage
collection cycle.
action=2 means a full allocation
failure.
action=3 means that a heap expansion
takes place.
action=4 means that all known soft
references are cleared.
action=5 means that stealing from
the transient heap is done.
action=6 means that free space is
very low.
25) What is SSL?
The Secure Sockets Layer (SSL) is a
protocol that provides secure communications between remote server processes or
endpoints. SSL security can be used for establishing communications inbound to
and outbound from an endpoint.
26) What are the siner certificates?
Signer certificates are used by
Java Secure Socket Extensions (JSSE) to validate certificates sent by the
remote side of the connection during a Secure Sockets Layer (SSL) handshake
27) What are the different GC policy algorithms in
IBM WebSphere Application Server V8 ?
IBM WebSphere Application Server V8
(on supported platforms) provides four different GC policy algorithms:
-Xgcpolicy:optthruput
-Xgcpolicy:optavgpause
-Xgcpolicy:gencon( Default)
-Xgcpolicy:balanced
IBM WebSphere Application Server V7
(on supported platforms) provides four different GC policy algorithms:
-Xgcpolicy:optthruput ( Default)
-Xgcpolicy:optavgpause
-Xgcpolicy:gencon
-Xgcpolicy:subpool
28) What
are the plugin parameters?
ConnectTimeout, ServerIOTimeout, RetryInterval, IgnoreAffinityRequests,
LoadBalanceWeight, MaxConnections.
ConnectTimeout identifies how long
(in seconds) the plugin will wait to get connect to WebSphere Application
Server (WAS). If the plugin waits longer than the value, it will mark the
server unavailable.
By default (without the parameter
set in the plugin-cfg.xml) or setting the value to 0, it represents a blocking
connect, that is, the thread will keep waiting to obtain a connection until the
operating system time out the request.
ServerIOTimeout identifies how long
(in seconds) the plugin will wait for the server to response to the request. If
the plugin waits longer than the value before the response is completed, it
will time out.
By default, the plugin uses blocked
I/O. So basically it will block wait until TCP connection times out.
RetryInterval is the time that the plug-in
will wait before trying again to use an appserver that was marked down.
MaxConnections : Max no. of
pending connections/requests for App server ,When the MaxConnections
limit is reached, the plug-in will stop sending requests to that appserver, but
it is not marked down
Please note that if the
MaxConnections limit has been reached the plug-in will not send ANY more
requests to that server until responses come back for the current PENDING
requests, and the pendingRequests count drops back down below the
MaxConnections limit.
29) How do you Determining whether OOM is a Java
OOM or Native OOM ?
If the stdout/stderr message says
that this is a java.lang.OutOfMemoryError, then this is a Java OOM.
If the stdout/stderr message says
that it failed to acquire memory, then this is a Native OOM.
30) What
is the effect of changing max heap and min heap size of a jvm same?
Using the same values is not
usually a good idea, because it delays the start of garbage collection until
the heap is full
Compaction moves objects closer and
further down in the heap, creating larger free areas near the top of the heap
Max memory used should be about
55-75% of the max heap size.
31) What
is nursery heap?
The nursery is a part of the heap
reserved for allocation of new objects.
32) Why
and when to perform name space binding?
Name space binding is used to
provide fixed qualified names for server application objects.
A deployed application requires
qualified fixed names if the application is accessed by thin client
applications or by J2EE client applications or server applications running in
another server process.
When you configure a name space
binding, you create a qualified fixed name for a server object. A fixed name
does not change if the object is moved to another server. A qualified fixed
name with a cell scope has the form: cell/persistent/fixedName
33) Name
space Binding types ?
1) String 2) EJB 3) CORBA 4) indirect
34) What
is Heap dump ?
A heap dump is a snapshot of the
memory of a Java process at a certain point of time. It shows live objects in
the memory and references between them.
You can use this option to debug
conditions such as memory leaks, heap fragmentation or to investigate what
objects are consuming the largest part of the memory
35) What
is Thread dump ?
A thread dump is a list of all the
Java threads that are currently active in a Java Virtual Machine (JVM).
36) What
is core dump and How to enable Core Dump function in linux?
A core dump is the printing or the
copying to a more permanent medium (such as a hard disk ) the contents of
random access memory ( RAM ) at one moment in time.
A core dump is taken mainly for the
purpose of debugging a program
enable core dump
If you enter “ulimit -c” command
and get the result value as 0, it indicate that core dump is disabled by
default, it would not generate core dump file.
We can use the command “ulimit -c
unlimited” to enable the core dump function, and does not limit the core dump
file size; if you need to restrict the size of the file, change the “unlimited”
as you want to generate the core file maximum size, pay attention to the unit
is blocks (KB).
Using the above command will only
effective for terminal current environment，
if you want to be permanent, you can modify the file
/etc/security/limits.conf file. add the below one line:
# /etc/security/limits.conf
#
#Each line describes a limit for a
user in the form:
#
#<domain>
<type> <item> <value>
<span style="color:
#008000;"> * soft
core unlimited</span>
37) What
is the use of generic JVM arguments?
The generic JVM arguments are used
to configure and adjust how the JVM executes. Once changes are made and saved
to the master configuration, the JVM requires a restart for the arguments to
take effect. Each JVM argument is separated by a space. This is also called
it's delimiter
or
Generic JVM arguments Specifies
command line arguments to pass to the Java virtual machine code that starts the
application server process.
Add the generic Jvm Arguments using
the WebSphere Admin Console or by editing the server.xml file:
Application Server
Ø In
the Administration Console select Servers
Ø Expand
Server Type and select WebSphere application servers
Ø Click
on the name of your server
Ø Expand
Java and Process Management and select Process Definition.
Ø Under
the Additional Properties section, click Java Virtual Machine.
Ø Scroll
down and locate the textbox for Generic JVM arguments.
1.Open the following file:
install_root/IBM/WebSphere/AppServer/profiles/AppSrv01/config/cells/<cellName>/nodes/<nodeName>/servers/server/server.xml
2.Find the jvmEntries element.
3.Add the following JVM options to
genericJVMArguments in server.xml and save the file:
genericJvmArguments="-Djava.awt.headless=true
-DamCryptoDescriptor.provider=IBMJCE
-DamKeyGenDescriptor.provider=IBMJCE
-Djavax.management.builder.initial=
/-Dcom.sun.management.jmxremote"
38) What
is core group?
A core group is a grouping of
WebSphere(R) Application Server cell processes. A core group can contain
stand-alone servers, cluster members, node agents, and the deployment manager.
A core group must contain at least one node agent or the deployment manager.
DefaultCoreGroup is a core group
that is created by default at installation time and can be used out-of-the-box;
that is, all processes will know about each other.
Note:
1. A core group cannot extend
beyond a cell
2. All JVMs in a core group must
able to communicate (they use heartbeat messages to know each other
A core group must be empty before
it can be deleted. The default core group cannot be deleted.
Each core group contains a core
group coordinator to manage its high availability relationships, and a set of
high availability policies that are used to manage the highly available
components within that core group. You can move processes from one core group
to another.
The following rules govern the core group
membership:
•Every process is a member of
exactly one core group.
•All members of a cluster must be
members of the same core group.
•Each core group must contain at
least one node agent or the deployment manager.
Core group coordinator: The core
group coordinator is responsible for coordinating high availability activities
between the core group members for which View Synchrony Protocol is
established.
We can change the default core
group coordinator by going to:
servers
–>coregroups->coregroup settings->Default Coregroup ->preferred
coordinator servers.
When a member becomes active
coordinator, you can see the following messages in the SystemOut:
[3/3/10 18:00:37:758 CET] 00000013
CoordinatorIm I HMGR0206I: The Coordinator is an Active Coordinator for core
group DefaultCoreGroup
If a new member joins the core
group, you can see the following message
[3/3/10 18:17:13:245 CET] 00000026
RoleMember I DCSV8051I: DCS Stack
DefaultCoreGroup.TestRepln at Member Test-Cell\node01\server01: Core group
membership set changed. Added: [Test-Cell\node02\server02]
39) How
do you decide which WebSphere Application Server process should be a core group
bridge?
Any WebSphere Application Server
process (dmgr, node agent, application server) can be a core group bridge
process for a core group. However, a process that you choose to be a core group
bridge should have production activities or response times that will not be
affected by the core group bridge workload. Node agents or application servers
that do not host any applications can be used as bridges, but it is best to use
dedicated non-clustered application servers that do not host applications, if
available system resources permit.
The dmgr process is similar to node
agents in that it does not handle real-time production traffic. However,
because dmgr represents a single point of failure and likely administers a
large number of servers in a topology with multiple core groups, it is best for
it not to have the added task of being a core group bridge.
40) What
happens when coordinator went down?
When the active coordinator is not
available (stopped/crashed), the HA manager will elect the first inactive
server in the preferred coordinator servers list. If preferred list is not
specified, it will select lexically lowest named server.
The newly selected coordinator
initiates a state rebuild by sending a message to all core group members to
report their states.
41) Which
servers need to be restarted after making core group bridge configuration
changes?
Core group bridge configuration
changes are not dynamic, and any time a bridge configuration change is made,
all of the affected bridges need to be restarted. Also, bridges can only
communicate with other bridges that have the same access point group
configuration. Consider this topology under different scenarios:
DefaultAccessPointGroup contains:
CoreGroup1:
Bridges:
bridgeServer1,bridgeServer2
Servers: cluster1Member1,
cluster1Member2
CoreGroup2:
Bridges:
bridgeServer3,bridgeServer4
Servers: cluster2Member1,
cluster2Member2
CoreGroup3:
Bridges: bridgeServer5,bridgeServer6
Servers: cluster3Member1,
cluster3Member2
Scenario A: CoreGroup4 and bridges
bridgeServer7 and bridgeServer8 are added to DefaultAccessPointGroup
The other six bridges
(bridgeServer1, bridgeServer2, bridgeServer3, bridgeServer4, bridgeServer5, and
bridgeServer6) will need to be restarted to recognize the new bridges in
CoreGroup4. Otherwise, CoreGroup1, CoreGroup2, and CoreGroup3 will continue to
communicate and exclude CoreGroup4, because CoreGroup4’s bridges have a
different access point group configuration defined.
Scenario B: Bridge bridgeServer2 is
stopped and removed from CoreGroup1; Bridge bridgeServer2b is added as a bridge
in CoreGroup1 to replace bridgeServer2
Bridges bridgeServer1,
bridgeServer3, bridgeServer4, bridgeServer5, and bridgeServer6 will need to be
restarted when bridgeServer2b is brought online. Otherwise, they will not be
able to communicate with bridgeServer2b.
Scenario C: Cluster1 (cluster1Member1
and cluster1Member2) gets moved from CoreGroup1 to CoreGroup2
Bridge configuration was not
changed and no bridges were moved, so none of the bridges need to be restarted.
Only the cluster1 members will need to be restarted when moved to CoreGroup2.
42) With
regard to server startup sequence, when should the core group bridges be
started?
A core group bridge does a
significant amount of work during startup. Using the proper server startup
sequence can reduce the amount of work that is done. The optimum order is:
1.Core group coordinators
2.Core group bridges
3.Clusters and other servers
Data is evenly distributed between
active core group bridges, and each time a bridge is started or stopped, the
data has to be redistributed. Therefore, it is more efficient to start the
bridges early on when there is little data (fewer servers started to post data)
in the core group to redistribute.
43) How
will core gorup identify Core group member Failure detection
HA manager monitors all the core
group members. It uses 2 settings to detect the failure
1. Active failure detection
If the heartbeat from a JVM is
failing for specified interval of time, then it will be marked as failed. When
using default settings, heartbeats are sent every 10sec and 20times (200sec)
should be failed before marking the JVM as failed. When a JVM is marked as
failed, a new view is installed and you can see that in the SystemOut log.
2. TCP Keep Alive
If one member is not able to
contact other member, and if gets closed socket error, it will signal the other
members to treat that member as failed. Say, if one jvm is panics or network
issue etc, as soon as the TCP settings allow, the failure will be detected.
Note: TCP Keep alive setting is of
the operating system.
44) Difference
between Java heap and Native heap memory
Java heap is the memory that the
JVM uses to allocate java objects.
Native heap is the memory that the
JVM uses for its own internal operations. JVM uses this area to load libraries
and for intermediate code generation.
Not all addressable memory is
available to a process. The operating system has its own requirements such as
1) The Kernel and 2) The runtime support
libraries
The addressable memory remaining is
often referred to as user space.
We define the native heap as Native
heap ="user space” - maximum Heap Size
45) What
is PermGen(Permanent Generation) Area ?
It is the area where class loading
and unloading happens. it stores metadata about classes , methods,etc.
46) What
is Old generation area?
The largest memory pool which should keep the
long living objects
47) What
is inside a WAS plugin configuration file?
Virtual host information
Cluster and Cluster member
information
URI mappings
Cluster loadbalancing algorithm
Plugin kdb ssl mappings
48) What
is the WAS plugin configuration file name?
plugin-cfg.xml
49) What
is the configuration file for IHS?
httpd.conf
50) What
is the httpd.conf file in IHS ?
This is the main IBM HTTP server
configuration file. It contains the
configuration directives that give the server its instructions.
ServerRoot
"/opt/IBM/HTTPServer"
PidFile
/srv/jas/logs/gpsprod/HTTPServer/prod0/httpd.pid
PidFile: The file in which the
server should record its process identification number when it starts.
DocumentRoot
"/srv/jas/data/gpsprod/HTTPServer/prod0/htdocs"
DocumentRoot: The directory out of which you
will serve your documents. By default, all requests are taken from this
directory, but symbolic links and aliases may be used to point to other
locations.
51) What
are the performance tuning parameter for IBM IHS?
ThreadLimit: maximum setting of
ThreadsPerChild
ServerLimit: maximum setting of
StartServers
StartServers: initial number of server
processes to start
MaxClients: maximum number of simultaneous
client connections
MinSpareThreads: minimum number of worker
threads which are kept spare
MaxSpareThreads: maximum number of worker
threads which are kept spare
ThreadsPerChild: constant number of worker
threads in each server process
MaxRequestsPerChild: maximum number of
requests a server process serves
ThreadLimit 256
ServerLimit 4
StartServers 2
MaxClients 600
MinSpareThreads 25
MaxSpareThreads 75
ThreadsPerChild 32
MaxRequestsPerChild 0
52) How do you gracefully shut down IHS?
In IHS 7.0 and later on Unix,
apachectl -k graceful-stop will stop listening for new requests but allow
active requests to finish, waiting forever by default, or until
GracefulShutdownTimeout seconds have elapsed.
Otherwise, there is no mechanism to
shut down the web server yet allow active requests to gracefully finish. Active
requests must finish within about 7 seconds, or they may be forcefully
terminated when the child process is killed.
53) How
does IBM HTTP Server determine when a child process should end? Does it have a
timeout?
There is no timeout .If
MaxRequestsPerChild is set to non-zero, a child process will exit once it has
handled that many client connections.
While there are more idle processes
than the value of MaxSpareServers, one child process will exit per second.*
require starting as root, or
changing the ownership or permission of existing log files, depending on the
configuration.
54) What
happens if I stop IBM HTTP Server using SIG KILL?
Stopping the server by sending
SIGTERM to the parent process
•no new connections will be
accepted, starting almost immediately
•existing requests will have a
short time to finish and log their results
•for most child processes: ◦the
active request will finish normally
◦the active request will be logged
•for child processes that don't
finish their request in a reasonable amount of time: ◦the request will be
abruptly terminated
◦the active request won't be logged
Stopping the server by sending
SIGKILL to all of the processes
•no new connections will be
accepted, starting almost immediately
•all active requests will be
abruptly terminated
•no active requests will be logged
•the pid file won't be removed, so
a warning will be logged when the server is started again
•no permanent problems expected
•Note: Third-party modules could
require manual intervention before restart if they have resources that they
must release at termination.
55) Why
are httpd processes still active when apachectl stop completes?
apachectl stop sends a signal to
the parent process, and then exits. As soon as the parent process receives the
signal, it starts terminating the child processes. In many cases, by the time
you can look for child processes after the completion of apachectl stop they
will have already exited. Some of the following are reasons why they will
linger for some time:
•high system load (perhaps caused
by many httpd child processes having to wake up and exit
•active requests being handled by
one or more httpd child processes
56) what
are the log levels in HIS
LogLevel: Control the number of messages logged to the
error log. Possible values include: debug, info, notice, warn, error, crit,
alert, emerg.
1) When i uninstall and installing
the application it was saying that application is already exist but it is not there in the installed path and
console .
then i check in the temp
folder the war file was not deleted so i
deleted the war file from the temp and synchronized the nodes then issues
resolved.
2) when i start the application it
was not coming up , then i check the logs i noticed Class not found error then
i checked the shared libs in the console and in the putty path , some jars
files are not there in the putty path then i asked application team some jars
files are not present in the path.
3) application team reported that
application is not responding when i check the logs i could see no space left
error .when i check whilc file system one of the file system was 100% then i
identified and removed unwanted files then issue got resolved.
4) when i try to uninstall the
application it was unable to install
1) Deploy the application
2) configuration changes like jvm
setting , connection pool settings
3) enabling traces
4) Generate and propagate the plugin
to webserver.
5) creating the resources like jdbc
providers and datasources.
6) Resolving the issues
57)
Installing a fix pack with silent
install on was 7.
This will describes how
to use the Update Installer for WebSphere Software to install the fix pack
using the silent install option.
Before you begin
The most recent version
of the Update Installer needs to be installed on a target system locally.
Use the Update
Installer program from the same user ID that installed the product that you are
updating. Otherwise, the file ownership mismatches might require correction by
the root user.
About this task
The most recent version
of the Update Installer needs to be installed on a target system locally.
Procedure
1.
Download
the required fix pack from the official IBM support Web site into<
WAS-ROOT>/maintenance directory.
2.
Ensure
that all running processes have been stopped.
3.
Edit
a response file. The one located at the bottom of the pane can be used as an
example. There are also sample response files found in the <WAS-ROOT>/responsefiles directory.
a.
Specify
the location of the product to the response file.
b.
Specify
the choice of install maintenance in the response file. For
example: -W update.type="install"
c.
Add
the maintenance location where packages can be found to the response file.
When
you install the fix pack, certain logic is used to determine which packages to
install. To find out more, refer to "Logic that the Update Installer uses
for system recommended installations," found at the bottom of this topic.
4.
Run
the Update Installer.
For
example:
Windows
update.bat -silent
-options "responsefiles\file_name"
Vista
update.exe -silent
-options "responsefiles\file_name"
AIX, Linux,Solaris
./update.sh
-silent -options "responsefiles/file_name"
5.
Review
the log file to verify maintenance has been installed successfully. The log can
be found atapp_server_root/logs/update/maintenance_package.install.
If for some reason the maintenance package is not applicable to install, a log
file found in <WAS-ROOT>/logs/tempX will list the reason for
the failure. The most recent log file, tmpX, where X refers to
the first available empty directory, will be created to reflect the status for
this attempted install. You might not receive an error message for a failed
installation in some cases. If you silently install a maintenance package and
you do not receive a response after a short period of time, view the logs. If
logs are not generated, then an invalid or missing argument might be causing
the installation to fail. Verify the Update Installer syntax for the command
line with the response files install.txt and uninstall.txt, located
in <WAS-ROOT>/responsefiles
Results
One of the following
results will appear in the log.
INSTCONFSUCCESS
The operation was a
success.
INSTCONFPARTIALSUCCESS
The operation was
partially successful, refer to the log for more details.
INSTCONFFAILED
The operation failed;
refer to the log for more details.
58) What
is new in WebSphere 8
1) Java virtual machine settings
Version 7.0 and previous versions
use the optthruput garbage collection algorithm. In Version 8.0, the default is
set to the generational garbage collector. This garbage collection algorithm
can increase performance. The following JVM option is added to the WebSphere
Application Server startup command: -Xgcpolicy:gencon. If you prefer to use the
optthruput garbage collection alogorithm, you can remove -Xgcpolicy:gencon and
the default optthruput garbage collection algorithm is used.
2) Application Server property
settings for a web server plug-in
The Use read/write timeout setting
on the administrative console corresponds to the ServerIOTimeout attribute in
the plugin-cfg.xml file. The default for the setting and the attribute for
Version 8 is 900 seconds. For Version 7, the default is 60 seconds. Before
Version 7, the default is 0.
3) Track admin changes
Another new administrative function
is the ability to track administrative configuration changes. This function
leverages the Extended Repository Checkpoint function from WebSphere Virtual
Enterprise, which writes out a delta repository each time configuration changes
are saved to the WebSphere Application Server configuration repository. The
delta repository lists the “before” and “after” configuration elements which
can then be used to track configuration changes.
59) Installing
and uninstalling a fix pack with silent install on WebSphere 8 ?
To install a fix pack from a
service repository, perform the following actions:a.Log on to your system.
1) Stop all servers and
applications on the WebSphere Application Server installation that is being
updated.
2) Change to the
Installation_Manager_binaries/eclipse/tools directory, where
Installation_Manager_binaries is the installation root directory for the
Installation Manager.
3)Install the fix pack.
[AIX] [HP-UX] [Linux] [Solaris]
./imcl install offering_ID_offering_version,optional_feature_ID
-repositories source_repository
-installationDirectory product_installation_location
-keyring keyring_file -password password
-acceptLicense
example :
/opt/IBM/InstallationManager/eclipse/tools/imcl install
8.0.0.0-WS-WASJavaSDK-LinuxX64-IFPI20798 -installationDirectory
/opt/IBM/WebSphere/AppServer -repositories
/tmp/20140924/base_products/multi/IBM
To uninstall
root@iedcajcdwia2:/root :
/opt/IBM/InstallationManager/eclipse/tools/imcl uninstall
8.0.0.0-WS-WASJavaSDK-LinuxX64-IFPI19109 -installationDirectory
/opt/IBM/WebSphere/AppServer
60) How
to copy files from one server to another server?
Use scp command
To copy a file from B to A while
logged into B:
scp /path/to/file
username@a:/path/to/destination
To copy a file from B to A while
logged into A:
scp username@b:/path/to/file
/path/to/destination
61) Is
it possible to run IBM HTTP Server as a non-root process on UNIX systems?
It is possible to run IBM HTTP
Server as a non-root process on a UNIX system, but when doing so, use only
nonstandard ports above 1024 and define user/group in the httpd.conf process.
When you start Http webserver as a wsadmin(non-root)
account we will get below error
(13)Permission denied: make_sock:
could not bind to address [::]:80
(13)Permission denied: make_sock:
could not bind to address 0.0.0.0:80
No listening
62) What information is available in plugin
cfg.xml file ?
Plugin.cfg.xml file contains detail
information about the application server
Plugin.config.xml contains the
below information...
1) Server configuration,
2) Cluster configuration,
3) Server weights,
4) Application virtual host.
63) Why do I need to enable SSO when using
form-based login in my WebSphere Application Server application?
By enabling SSO, WebSphere
Application Server maintains user state as an LTPA cookie across Web requests.
If SSO is not enabled, each individual request requires authentication. If you
choose to use form-based login, once the form completes authenticating, the
user then redirects back to the originally requested URL. Without SSO, the
user's authentication is now lost and the authorization will fail. This is not
seen when using basic authentication because the authentication information is
in every HTTP request and WebSphere Application Server can use it whenever
needed (this does impact both security and performance).
64) What
is signer certificates?
A signer certificate represents a
certificate and public key associated with some personal certificate. The
purpose of the signer certificate is to verify personal certificates
65) What
is personal certificates ?
A personal certificate represents
the identity of the end point and contains a public and private key for
signing/encrypting data.
66) What
is a Keystore file ?
The keystore file is a key database
file that contains both public keys and private keys. Public keys are stored as
signer certificates while private keys are stored in the personal certificates.
The keys are used for a variety of purposes, including authentication and data
integrity. You can use both the key management utility (iKeyman) and the
keytool utility to create.
67) What
is Truststore file ?
A truststore file is a key database
file that contains the public keys for target servers. The public key is stored
as a signer certificate. If the target uses a self-signed certificate, extract
the public certificate from the server keystore file. Add the extracted
certificate into the truststore file as a signer certificate. For a commercial
certificate authority (CA), the CA root certificate is added. The truststore
file can be a more publicly accessible key database file that contains all the
trusted certificates
Default self-signed certificate
configuration
By default, WebSphere Application
Server creates a unique self-signed certificate for each node.
WebSphere Application Server no
longer relies on the default or dummy certificate that is shipped with the
product. The key.p12 default keystore and the trust.p12 truststore are stored
in the configuration repository within the node directory.
All of the nodes put their signer
certificates in this common truststore (trust.p12).
Additionally, after you federate a
node, the default SSL configuration is automatically modified to point to the
common truststore, which is located in the cell directory. The node can now
communicate with all other servers in the cell.
All default SSL configurations
contain a keystore with the name suffix DefaultKeyStore and a truststore with
the name suffix DefaultTrustStore.
These default suffixes instruct the
WebSphere Application Server runtime to add the signer of the personal
certificate to the common truststore. If a keystore name does not end with
DefaultKeyStore, the keystore signer certificates are not added to the common
truststore when you federate the server.
You can change the default SSL configuration,
but you must ensure that the correct trust is established for administrative
connections, among others.
For more information, see Default
self-signed certificate configuration and Web server plug-in default
configuration
The default password for the
keystore is WebAS. You can change the default keystore password by using either
the administrative console or the appropriate AdminTask command.
68) We
have some issue with our application server and we tried killing it using
kill-9 command, the process disappeared for few seconds but it is back again.
We did not start the server but it started. What would be the reason?
Servers --> Application Servers
--> server_name. Then, under Server Infrastructure,
click Java and Process Management
--> Process Definition --> process --> Monitoring Policy.
Here we have an option Automatic
Restart, this Specifies whether the process should restart automatically if it
fails. On distributed systems, the default is to restart the process
automatically.
69) Why
can't we start node agent from console in websphere application server?
Node agent is a interface,
communicator b/w servers and dmgr.. But there is not interface between dmgr and
nodeagent. nodeagent behaves like manager to itself..once you start the
nodeagent you can give commands like stop, start jvms in the similar way you
can stop and restart the node agent as it is running..if nodeagent stopped, if
you are issuing command like start nodeagent which process is going to receive
the command.
70) How
to get the password of .kdb file if we forget?
Once you have create the .kdb file
this file related passwords are stored into .sth file it will be stored into
the same directory.in the .sth file contains the .kdb file password in
encrypted format.
71) How
i can know how many users are hitting the application? If any command is there
to find out the hit-counts?
You have to check in error.log
Using monitoring tool introscope willy
72) How
will find out request is static or dynamic by webserver?
The way it works is first you
install web server and copy your static content such as .js, .css files, images
on the web server. Then you install a plug-in on web server. Plug-in takes a
look at the incoming request and depending on the URL it decides if this is the
request for static content or dynamic content, if it is request for dynamic
content it forwards control to WAS.A web server plug-in is specific to the type
of web server. It is installed on the web server machine and configured in the
web server configuration.
73) How
we can check application is running or not in websphere by command line
utilities ?
grep the application name in
systemout.log.
74) Is there a way i can start my server along
with nodeagent ?
Servers--> Application Servers
--> server_name. Then, under Server
Infrastructure,
click Java and Process Management --> Process
Definition --> process --> Monitoring Policy.
Here we have an option Node Restart State
which specifies the desired behavior of the servers after the node completely
shuts down and restarts.
STOPPED - node agent does not start the server.
RUNNING - the node agent always starts the server.
PREVIOUS - the node agent starts the server only if the server was
running when the node agent stopped.
75) How
to take the backup of EAR or WAR file using command line?
76) What
is the command to see the content of zip file without extract?
77) What
is the DocumentRoot in webserver?
78) What
is Hybrid horizontal and vertical clustering?
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