Liferay Clustering

INTRODUCTION

Once you are done with website portal development you need to make sure that the application is having a high availability and minimum of downtime. To make sure application can handle more requests and arrange for more guaranteed uptime here is a sample Liferay clustering set up.

There can be various clustering configurations based on the availability of webservers, load balancers, application servers and database servers.

This document gives a complete clustering based on below components:

1. Apache Web server (1)
2.  Liferay Tomcat Application Servers (2)
3.   Postgres DB server (1) 
4.   Actual Physical Servers (3)

SAMPLE SETUP DIAGRAM

Below is the sample clustering used.

 

WEB SERVER CONFIGURATIONS

Pre-requisites:

a.     Apache Web Server must be installed.

b.     MOD_JK must be installed

1.             In /etc/httpd/conf

Add below entries at the end in httpd.conf file

 

<VirtualHost 10.66.70.184:80>   ServerName acc01.ad.test.com   JkMount / loadbalancer   JkMount /* loadbalancer </VirtualHost> #Load the mod_jk connector # Include mod_jk's specific configuration file  Include conf/mod_jk.conf

2.             In /etc/httpd/conf

Add below entries at the end in mod_jk.conf file, create a mod_jk.conf file if it is not there

# Load mod_jk module # Specify the filename of the mod_jk lib LoadModule jk_module modules/mod_jk.so # Where to find workers.properties JkWorkersFile conf/workers.properties # Where to put jk logs JkLogFile logs/mod_jk.log # Set the jk log level [debug/error/info] JkLogLevel info # Select the log format JkLogStampFormat  "[%a %b %d %H:%M:%S %Y]" # JkOptions indicates to send SSK KEY SIZE JkOptions +ForwardKeySize +ForwardURICompat -ForwardDirectories # JkRequestLogFormat JkRequestLogFormat "%w %V %T"                # Mount your applications JkMount /* loadbalancer # Add shared memory. # This directive is present with 1.2.10 and # later versions of mod_jk, and is needed for # for load balancing to work properly JkShmFile logs/jk.shm               # Add jkstatus for managing runtime data <Location /jkstatus/>     JkMount status     Order deny,allow     Deny from all     Allow from 127.0.0.1 </Location>

 

3.             In /etc/httpd/conf

Add below entries at the end in workers.properties file, create a workers.properties file if it is not there

# Define list of workers that will be used # for mapping requests worker.list=loadbalancer,status # Define Node1 # modify the host as your host IP or DNS name. worker.node1.port=8009 worker.node1.host=10.66.70.184 worker.node1.type=ajp13 worker.node1.lbfactor=1 worker.node1.socket_timeout=60 worker.node1.connection_pool_timeout=60 worker.node1.ping_mode=A worker.node1.ping_timeout=20000 worker.node1.connect_timeout=20000 # Define Node2 # modify the host as your host IP or DNS name. worker.node2.port=8009 worker.node2.host=10.66.70.185 worker.node2.type=ajp13 worker.node2.lbfactor=1 worker.node2.socket_timeout=60 worker.node2.connection_pool_timeout=60 worker.node2.ping_mode=A worker.node2.ping_timeout=20000 worker.node2.connect_timeout=20000 # Load-balancing behaviour worker.loadbalancer.type=lb worker.loadbalancer.balance_workers=node1,node2 worker.loadbalancer.sticky_session=1 # Status worker for managing load balancer worker.status.type=status

4.         In /etc/httpd/modules

Add the mod_jk.so file if not there. This is basically a header/library file with version which we need to include.

 

LIFERAY TOMCAT APPLICATION SERVER CONFIGURATIONS

Pre-requisites:

a.     Liferay Tomcat must be installed / copied in the required directory.

Note: All the below mentioned file entries from point 1 to 7 must be there in both the application nodes.

  

1.             In    /home/admin/liferay-portal-6.1.1-ce-ga2

Create portal-ext.properties file if it is not there and add the below entries

 

#Below are database entries to connect to database jdbc.default.driverClassName=org.postgresql.Driver jdbc.default.url=jdbc:postgresql://10.66.70.183:5432/liferay24feb2014 jdbc.default.username=postgres jdbc.default.password=postgres #Below is DB server IP for outgoing link cluster.link.autodetect.address=10.66.70.183:5432 #Below entries are required to enable EHCACHE net.sf.ehcache.configurationResourceName=/ehcache/hibernate-clustered.xml ehcache.multi.vm.config.location=/ehcache/liferay-multi-vm-clustered.xml #Below entries are required for tomcat clustering cluster.link.enabled=true lucene.replicate.write=true ehcache.cluster.link.replication.enabled=true web.server.display.node=true org.quartz.jobStore.isClustered=true ehcache.bootstrap.cache.loader.factory=com.liferay.portal.cache.ehcache.JGroupsBootstrapCacheLoaderFactory ehcache.cache.event.listener.factory=net.sf.ehcache.distribution.jgroups.JGroupsCacheReplicatorFactory ehcache.cache.manager.peer.provider.factory=net.sf.ehcache.distribution.jgroups.JGroupsCacheManagerPeerProviderFactory # Set this to true to enable the cluster executor debugging. This will # attach a debugging listener which will log every cluster event it receives. cluster.executor.debug.enabled=true

2.             In   /home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/bin

In setenv.sh file add the below entries

JAVA_OPTS="$JAVA_OPTS -Dfile.encoding=UTF8 -Dorg.apache.catalina.loader.WebappClassLoader.ENABLE_CLEAR_REFERENCES=false -Duser.timezone=IST -Xmx1024m -XX:MaxPermSize=256m -Djgroups.bind_addr=10.66.70.184 -Djava.net.preferIPv4Stack=true"

3.             In   /home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/conf

In web.xml file add the below entries at the end just before closing tag </web-app>

<distributable/>

4.             In   /home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/conf

In server.xml file add the below entries

For NODE 1

<Engine name="Catalina" defaultHost="localhost" jvmRoute="node1">

For NODE 2

<Engine name="Catalina" defaultHost="localhost" jvmRoute="node2">

For both the nodes add below entry in between <Engine> </Engine> opening and closing tag

<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"        channelSendOptions="6">     <Manager className="org.apache.catalina.ha.session.BackupManager"        expireSessionsOnShutdown="false"        notifyListenersOnReplication="true"        mapSendOptions="6"/>          <Channel className="org.apache.catalina.tribes.group.GroupChannel">     <Membership className="org.apache.catalina.tribes.membership.McastService"        address="228.0.0.4"        port="45564"        frequency="500"        dropTime="3000"/>     <Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver"       address="auto"        port="5000"        selectorTimeout="100"        maxThreads="6"/>     <Sender className="org.apache.catalina.tribes.transport.ReplicationTransmitter">       <Transport className="org.apache.catalina.tribes.transport.nio.PooledParallelSender"/>     </Sender>     <Interceptor className="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector"/>     <Interceptor className="org.apache.catalina.tribes.group.interceptors.MessageDispatch15Interceptor"/>     <Interceptor className="org.apache.catalina.tribes.group.interceptors.ThroughputInterceptor"/>   </Channel>   <Valve className="org.apache.catalina.ha.tcp.ReplicationValve"         filter=".*\.gif;.*\.js;.*\.jpg;.*\.png;.*\.htm;.*\.html;.*\.css;.*\.txt;"/>   <ClusterListener className="org.apache.catalina.ha.session.ClusterSessionListener"/> </Cluster>

5.             In   /home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/conf

In context.xml file add the below entries

<Context distributable="true">

  

6.             In   /home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/webapps /ROOT/WEB-INF/classes/ehcache

Create an ehcache folder if not there also add a file hibernate-clustered.xml with below entries.

<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="ehcache.xsd">         <diskStore path="ehcache.disk.store.dir/hibernate" />         <cacheManagerEventListenerFactory class="" properties="" />         <cacheManagerPeerProviderFactory                 class="net.sf.ehcache.distribution.jgroups.JGroupsCacheManagerPeerProviderFactory"                 properties="connect=TCP(bind_port=${jgroups.bind_port:7700};port_range=5;loopback=true;recv_buf_size=20M;send_buf_size=640K;discard_incompatible_packets=true;max_bundle_size=64K;max_bundle_timeout=30;enable_bundling=true;use_send_queues=true;sock_conn_timeout=300;timer_type=new;timer.min_threads=4;timer.max_threads=10;timer.keep_alive_time=3000;timer.queue_max_size=500;thread_pool.enabled=true;thread_pool.min_threads=1;thread_pool.max_threads=10;thread_pool.keep_alive_time=5000;thread_pool.queue_enabled=false;thread_pool.queue_max_size=100;thread_pool.rejection_policy=discard;oob_thread_pool.enabled=true;oob_thread_pool.min_threads=1;oob_thread_pool.max_threads=8;oob_thread_pool.keep_alive_time=5000;oob_thread_pool.queue_enabled=false;oob_thread_pool.queue_max_size=100;oob_thread_pool.rejection_policy=discard):                            TCPPING(initial_hosts=${jgroups.tcpping.initial_hosts};port_range=10;timeout=3000;num_initial_members=3):                            VERIFY_SUSPECT(timeout=1500):                            MERGE2(min_interval=10000;max_interval=30000):                            FD_SOCK():                            FD(timeout=3000;max_tries=3):                            BARRIER():                            pbcast.NAKACK(use_mcast_xmit=false;gc_lag=0;retransmit_timeout=300,600,1200,2400,4800;discard_delivered_msgs=true):                            UNICAST(timeout=300,600,1200):                            pbcast.GMS(join_timeout=5000;join_retry_timeout=2000;print_local_addr=true):                            pbcast.STABLE(stability_delay=1000;desired_avg_gossip=50000;max_bytes=4M):                            UFC(max_credits=2M;min_threshold=0.4):                            MFC(max_credits=2M;min_threshold=0.4):                            FRAG2(frag_size=60K):                            pbcast.STREAMING_STATE_TRANSFER()"                 propertySeparator="::"         />         <cacheManagerPeerListenerFactory                 class="net.sf.ehcache.distribution.RMICacheManagerPeerListenerFactory"         />         <!--         Hibernate will use the defaultCache unless custom configurations are defined         below for individual domain objects, collection, queries, etc.         -->         <defaultCache                 maxElementsInMemory="10000"                 eternal="false"                 timeToIdleSeconds="30"                 overflowToDisk="false"         >         <cacheEventListenerFactory                         class="net.sf.ehcache.distribution.jgroups.JGroupsCacheReplicatorFactory"                         properties="replicatePuts=false,replicateUpdatesViaCopy=false"                         propertySeparator=","                 />                 <bootstrapCacheLoaderFactory class="net.sf.ehcache.distribution.jgroups.JGroupsBootstrapCacheLoaderFactory" />         </defaultCache>         <!--     Tracks the timestamps of the most recent updates to particular tables. It is     important that the cache timeout of the underlying cache implementation be     set to a higher value than the timeouts of any of the query caches. In fact,     it is recommend that the the underlying cache not be configured for expiry     at all.     -->         <cache                 name="org.hibernate.cache.UpdateTimestampsCache"                 maxElementsInMemory="5000"                 eternal="true"                 overflowToDisk="false"         >         <cacheEventListenerFactory                         class="net.sf.ehcache.distribution.jgroups.JGroupsCacheReplicatorFactory"                 />                 <bootstrapCacheLoaderFactory class="net.sf.ehcache.distribution.jgroups.JGroupsBootstrapCacheLoaderFactory" />         </cache>         <!--         The cache name is the same as the class name specified in your Hibernate         mapping file.         -->         <cache                 name="com.liferay.portal.model.impl.UserImpl"                 maxElementsInMemory="10000"                 eternal="false"         timeToIdleSeconds="30"                 overflowToDisk="false"         >         <cacheEventListenerFactory                         class="net.sf.ehcache.distribution.jgroups.JGroupsCacheReplicatorFactory"                         properties="replicatePuts=false,replicateUpdatesViaCopy=false"                         propertySeparator=","                 />                 <bootstrapCacheLoaderFactory class="net.sf.ehcache.distribution.jgroups.JGroupsBootstrapCacheLoaderFactory" />         </cache> </ehcache>

7.  In   /home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/webapps/ROOT/WEB-INF/classes/ehcache

Create a ehcache folder if not there also add a file liferay-multi-vm-clustered.xml with below entries.

<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="ehcache.xsd">         <!--         Caches in this file can be clustered and are configured to be clustered.         -->         <diskStore path="ehcache.disk.store.dir/liferay-multi-vm" />         <cacheManagerEventListenerFactory class="" properties="" />         <cacheManagerPeerProviderFactory                 class="net.sf.ehcache.distribution.jgroups.JGroupsCacheManagerPeerProviderFactory"                 properties="connect=TCP(bind_port=7800;port_range=5;loopback=true;recv_buf_size=20M;send_buf_size=640K;discard_incompatible_packets=true;max_b undle_size=64K;max_bundle_timeout=30;enable_bundling=true;use_send_queues=true;sock_conn_timeout=300;timer_type=new;timer.min_threads=4;timer.max_threads=10;t imer.keep_alive_time=3000;timer.queue_max_size=500;thread_pool.enabled=true;thread_pool.min_threads=1;thread_pool.max_threads=10;thread_pool.keep_alive_time=5 000;thread_pool.queue_enabled=false;thread_pool.queue_max_size=100;thread_pool.rejection_policy=discard;oob_thread_pool.enabled=true;oob_thread_pool.min_threa ds=1;oob_thread_pool.max_threads=8;oob_thread_pool.keep_alive_time=5000;oob_thread_pool.queue_enabled=false;oob_thread_pool.queue_max_size=100;oob_thread_pool .rejection_policy=discard):                            TCPPING(initial_hosts=${jgroups.tcpping.initial_hosts};port_range=10;timeout=3000;num_initial_members=3):                            VERIFY_SUSPECT(timeout=1500):                            MERGE2(min_interval=10000;max_interval=30000):                            FD_SOCK():                            FD(timeout=3000;max_tries=3):                            BARRIER():                            pbcast.NAKACK(use_mcast_xmit=false;gc_lag=0;retransmit_timeout=300,600,1200,2400,4800;discard_delivered_msgs=true):                            UNICAST(timeout=300,600,1200):                            pbcast.GMS(join_timeout=5000;join_retry_timeout=2000;print_local_addr=true):                            pbcast.STABLE(stability_delay=1000;desired_avg_gossip=50000;max_bytes=4M):                            UFC(max_credits=2M;min_threshold=0.4):                            MFC(max_credits=2M;min_threshold=0.4):                            FRAG2(frag_size=60K):                            pbcast.STREAMING_STATE_TRANSFER()"                 propertySeparator="::"         />         <cacheManagerPeerListenerFactory                 class="net.sf.ehcache.distribution.RMICacheManagerPeerListenerFactory"         />         <defaultCache                 maxElementsInMemory="10000"                 eternal="false"         timeToIdleSeconds="30"                 overflowToDisk="false"         >         <cacheEventListenerFactory                         class="net.sf.ehcache.distribution.jgroups.JGroupsCacheReplicatorFactory"                         properties="replicatePuts=false,replicateUpdatesViaCopy=false"                         propertySeparator=","                 />                 <bootstrapCacheLoaderFactory class="net.sf.ehcache.distribution.jgroups.JGroupsBootstrapCacheLoaderFactory" />         </defaultCache>         <cache                 name="com.liferay.portal.kernel.dao.orm.FinderCache"                 maxElementsInMemory="10000"                 eternal="false"         timeToIdleSeconds="30"                 overflowToDisk="false"         >         <cacheEventListenerFactory                         class="net.sf.ehcache.distribution.jgroups.JGroupsCacheReplicatorFactory"                         properties="replicatePuts=false,replicateUpdatesViaCopy=false"                         propertySeparator=","                 />                 <bootstrapCacheLoaderFactory class="net.sf.ehcache.distribution.jgroups.JGroupsBootstrapCacheLoaderFactory" />         </cache>         <cache                 name="com.liferay.portal.security.permission.PermissionCacheUtil"                 maxElementsInMemory="10000"                 eternal="false"         timeToIdleSeconds="30"                 overflowToDisk="false"         >         <cacheEventListenerFactory                         class="net.sf.ehcache.distribution.jgroups.JGroupsCacheReplicatorFactory"                         properties="replicatePuts=false,replicateUpdatesViaCopy=false"                         propertySeparator=","                 />                 <bootstrapCacheLoaderFactory class="net.sf.ehcache.distribution.jgroups.JGroupsBootstrapCacheLoaderFactory" />         </cache>         <cache                 name="com.liferay.portal.service.impl.PortletPreferencesLocalUtil"                 maxElementsInMemory="10000"                 eternal="false"         timeToIdleSeconds="30"                 overflowToDisk="false"         >         <cacheEventListenerFactory                         class="net.sf.ehcache.distribution.jgroups.JGroupsCacheReplicatorFactory"                         properties="replicatePuts=false,replicateUpdatesViaCopy=false"                         propertySeparator=","                 />                 <bootstrapCacheLoaderFactory class="net.sf.ehcache.distribution.jgroups.JGroupsBootstrapCacheLoaderFactory" />         </cache>         <cache                 name="com.liferay.portal.servlet.filters.cache.CacheUtil"                 maxElementsInMemory="1000"                 eternal="false"                 timeToLiveSeconds="3600"                 overflowToDisk="false"         >         <cacheEventListenerFactory                         class="net.sf.ehcache.distribution.jgroups.JGroupsCacheReplicatorFactory"                         properties="replicatePuts=false,replicateUpdatesViaCopy=false"                         propertySeparator=","                 />                 <bootstrapCacheLoaderFactory class="net.sf.ehcache.distribution.jgroups.JGroupsBootstrapCacheLoaderFactory" />         </cache>         <cache                 name="com.liferay.portlet.calendar.service.impl.CalEventLocalUtil"                 maxElementsInMemory="10000"                 eternal="false"         timeToIdleSeconds="30"                 overflowToDisk="false"         >         <cacheEventListenerFactory                         class="net.sf.ehcache.distribution.jgroups.JGroupsCacheReplicatorFactory"                         properties="replicatePuts=false,replicateUpdatesViaCopy=false"                         propertySeparator=","                 />                 <bootstrapCacheLoaderFactory class="net.sf.ehcache.distribution.jgroups.JGroupsBootstrapCacheLoaderFactory" />         </cache>         <!--         <cache                 name="com.liferay.portlet.journalcontent.util.JournalContentUtil"                 maxElementsInMemory="1000"                 eternal="false"                 timeToLiveSeconds="3600"                 overflowToDisk="false"         >         <cacheEventListenerFactory                         class="net.sf.ehcache.distribution.jgroups.JGroupsCacheReplicatorFactory"                         properties="replicatePuts=false,replicateUpdatesViaCopy=false"                         propertySeparator=","                 />                 <bootstrapCacheLoaderFactory class="net.sf.ehcache.distribution.jgroups.JGroupsBootstrapCacheLoaderFactory" />         </cache>         --> </ehcache>

POSTGRES DATABASE SERVER CONFIGURATIONS

1.             In   /opt/PostgreSQL/9.2/data

In pg_hba.conf file add the below entries at the end

#Below entry allow all IP's and all usernames to connect to all databases  connections host    all             all              0.0.0.0/0              md5

 

FILES AND LOCATION CHECKLIST

						Checklist
	Node	Applications	Operating System	Locations	S.No	Files Modified	Location of file
WEBSERVER	1	Apache/2.2.15	Red Hat Enterprise Linux	10.66.70.184	1	httpd.conf	/etc/httpd/conf
		mod_jk/1.2.31	Server release 6.2 (Santiago)		2	mod_jk.conf	/etc/httpd/conf
					3	mod_jk.so	/etc/httpd/modules
					4	workers.properties	/etc/httpd/conf
LIFERAY PORTAL	1	liferay-portal-6.1.1-ce-ga2	Red Hat Enterprise Linux	10.66.70.184	1	context.xml	/home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/conf
			Server release 6.2 (Santiago)		2	server.xml	/home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/conf
					3	web.xml	/home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/conf
					4	setenv.sh	/home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/bin
					5	portal-ext.properties	/home/admin/liferay-portal-6.1.1-ce-ga2
					6	hibernate-clustered.xml	/home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/webapps/ROOT/WEB-INF/classes/ehcache
					7	liferay-multi-vm-clustered.xml	/home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/webapps/ROOT/WEB-INF/classes/ehcache
LIFERAY PORTAL	2	liferay-portal-6.1.1-ce-ga2	Red Hat Enterprise Linux	10.66.70.185	1	context.xml	/home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/conf
			Server release 6.2 (Santiago)		2	server.xml	/home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/conf
					3	web.xml	/home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/conf
					4	setenv.sh	/home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/bin
					5	portal-ext.properties	/home/admin/liferay-portal-6.1.1-ce-ga2
					6	hibernate-clustered.xml	/home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/webapps/ROOT/WEB-INF/classes/ehcache
					7	liferay-multi-vm-clustered.xml	/home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/webapps/ROOT/WEB-INF/classes/ehcache
DATABASE	1	postgresql-9.2.6-1-linux-x64	Red Hat Enterprise Linux	10.66.70.183	1	pg_hba.conf	/opt/PostgreSQL/9.2/data
			Server release 6.2 (Santiago)

LINUX COMMANDS USED

S.No	Command	Description	Output
1	httpd –v	To find apache version	Server version: Apache/2.2.15 (Unix) Server built:   Oct  6 2011 11:06:33
2	(strings /PATH/TO/APACHE/modules/mod_jk.so |grep -i mod_jk)  strings /usr/lib64/httpd/modules/mod_jk.so |grep -i mod_jk	To find mod_jk version	mod_jk.so mod_jk.c mod_jk/1.2.31 (1026297) logs/mod_jk.log
3	cat /etc/*-release	To find Linux Version	Red Hat Enterprise Linux Server release 6.2 (Santiago)
4	./pg_ctl -D /opt/PostgreSQL/9.2/data stop -m immediate	To immediately stop Postgres from /opt/PostgreSQL/9.2/bin
5	./pg_ctl -D /opt/PostgreSQL/9.2/data start	To start Postgres from /opt/PostgreSQL/9.2/bin
6	./pg_ctl -D /opt/PostgreSQL/9.2/data stop	To stop Postgres from /opt/PostgreSQL/9.2/bin
7	./pg_ctl -D /opt/PostgreSQL/9.2/data status	To check status from /opt/PostgreSQL/9.2/bin	server is running (PID: 50933)
8	/etc/init.d/httpd status	To check status from apache httpd service	httpd (pid  3062) is running…
9	/etc/init.d/httpd start	To start apache httpd service
10	/etc/init.d/httpd stop	To stop apache httpd service
11	./startup.sh	To start Liferay tomcat from /home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/bin/
12	./shutdown.sh	To stop Liferay tomcat from /home/admin/liferay-portal-6.1.1-ce-ga2/tomcat-7.0.27/bin/
13	showmount -e 10.66.70.185
14	mount -t nfs 10.66.70.185:/home/admin/documents_library /home/admin/documents_library
15	service iptables status	To check status of firewall service
16	service iptables start	To start firewall service
17	service iptables stop	To stop firewall service
18	service rpcbind status	To check status of  rpcbind service
19	service rpcbind start	To start rpcbind service
20	service rpcbind stop	To stop rpcbind service
21	service nfs status	To check status of  nfs service
22	service nfs start	To start nfs service
23	service nfs stop	To stop nfs service
24	ps -ef | grep tomcat
25	netstat -nap | grep 111	To find which service is running on port 111
26	rpm -ivh portmap-4.0-65.2.2.1.x86_64.rpm	To install and rpm
27	chmod -R 777 <file/folder name>	To give read/write/access permission to folder/file
28	yum remove java	To uninstall java completey