Decommission a data node in HDP

From Ambari :

Manually :
[root@namenode1 conf]# pwd
/etc/hadoop/conf
[root@namenode1 conf]# ll | grep dfs.exclude
-rw-r--r--. 1 hdfs hadoop     1 Jan 12 15:32 dfs.exclude
[root@namenode1 conf]# cat dfs.exclude

[root@namenode1 conf]# vi dfs.exclude
[root@namenode1 conf]# cat dfs.exclude
edgenode.hdp.cn
[root@namenode1 conf]# su - hdfs
Last login: Sun Jan 12 15:33:08 EST 2020
[hdfs@namenode1 ~]$ hdfs dfsadmin -refreshNodes
Refresh nodes successful

[hdfs@namenode1 ~]$

Disable Resource Manager HA

1. Stop YARN and Zookeeper services from ambari
2. From Ambari-server :

                                           /var/lib/ambari-server/resources/scripts/configs.py --user=admin --     
                                                             password=admin --host=edgenode.hdp.cn --cluster=hdpdev --
                                                             action=get --config-      type=yarn-site -f yarn-site.json

3. From the below change the first property to value "false" and remove the other properties from yarn-site.json

                                       a) "yarn.resourcemanager.ha.enabled": "false",

                                  b) "yarn.resourcemanager.ha.rm-ids": "rm1,rm2",

                                  c) "yarn.resourcemanager.hostname.rm1": "datanode1.hdp.cn",

                                  d) "yarn.resourcemanager.hostname.rm2": "edgenode.hdp.cn",

                                  e)  "yarn.resourcemanager.webapp.address.rm1": "datanode1.hdp.cn:8088",

                                  f)  "yarn.resourcemanager.webapp.address.rm2": "edgenode.hdp.cn:8088",

                                 g) "yarn.resourcemanager.webapp.https.address.rm1": "datanode1.hdp.cn:8090",

                                 h) "yarn.resourcemanager.webapp.https.address.rm2": "edgenode.hdp.cn:8090",

                                 i) "yarn.resourcemanager.cluster-id": "yarn-cluster",

                                 j) "yarn.resourcemanager.ha.automatic-failover.zk-base-path": "/yarn-leader-election",

4. Set the below properties to existing resource manager

                                   a)  "yarn.resourcemanager.hostname":

                               b) "yarn.resourcemanager.admin.address":

                               c) "yarn.resourcemanager.webapp.address":                                                             

                               d)"yarn.resourcemanager.resource-tracker.address":                 

                               e)"yarn.resourcemanager.scheduler.address":

                                f)"yarn.resourcemanager.webapp.https.address":

                                g)"yarn.timeline-service.webapp.address":

                                h)"yarn.timeline-service.webapp.https.address":

                                 i)"yarn.timeline-service.address":

                                 j)"yarn.log.server.url":

5. Copy the yarn-site.json file back to the ambari-server and run the below command to set the changes made

                                            /var/lib/ambari-server/resources/scripts/configs.py --user=admin --password=admin --                                           host=edgenode.hdp.cn --cluster=hdpdev --action=get --config-type=yarn-site

6. Delete the Resource Manager host comonent

                                         curl --user admin:admin -i -H "X-Requested-By: ambari" -X  DELETE  
                                    http://edgenode.hdp.cn:8080/api/v1/clusters/hdpdev/hosts/edgenode.hdp.cn/
                                    host_components/RESOURCEMANAGER
                                                                                                                                                                                                        

7. Start zookeeper service from Ambari.

8. On  zookeeper clients run the below command to change the znode permissions

                                       /usr/hdp/current/zookeeper-client/bin/zkCli.sh getAcl /rmstore/ZKRMStateRoot

                                 /usr/hdp/current/zookeeper-client/bin/zkCli.sh setAcl /rmstore/ZKRMStateRoot                                                       world:anyone:rwcda

9. From Ambari UI, restart zookeeper service and YARN service

Yarn Capacity Scheduler

1. /etc/hadoop/conf/yarn-site.xml                                                                                                                                                                                    yarn.resourcemanager.scheduler.class=org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler

2. Capacity Scheduler settings (/etc/hadoop/conf/capacity-scheduler.xml on resource manager host)

  

   a) Queues are fundamental unit of scheduling in yarn

               yarn.scheduler.capacity.root.queues = support,engineering,marketing     (parent queues)

                       yarn.scheduler.capacity.support.queues=training,services                (leaf queues)

                       yarn.scheduler.capacity.engineering=development,qa                       (leaf queues)

                       yarn.scheduler.capacity.marketing=sales,advertising                         (leaf queues)

 

             b) Capacity Scheduler ACL's

                        

                         Queue users:

                         yarn.scheduler.capacity.root.acl_submit_application=      (asterisk == all users and groups & empty space == deny all users and groups)

                                  yarn.scheduler.capacity.support.acl_submit_applications= sherlock,pacioli,njella hg_group,cd_group

                                  yarn.scheduler.capacity.engineering.acl_submit_applications=user1,user2,user3 group1,group2,group3

                                  yarn.scheduler.capacity.marketing.acl_submit_applications= user4,user2,user5, group4,group5,group6

               Queue Administers

                         yarn.scheduler.capacity.root.acl_administer_queue=

                                  yarn.scheduler.capacity.support.acl_administer_queue= support_admin_group

                                  yarn.scheduler.capacity.engineering.acl_administer_queue=engineering_admin_group

                                  yarn.scheduler.capacity.marketing.acl_administer_queue=engineering_Admin_grp

   c) Queue Mappings:

               

               Setting Up Queue Mappings

                         yarn.scheduler.capacity.queue-mappings=u:njella:engineering,u:chitra:marketing,g:engineering_group:engineering

                         If group name is same as queue name then

                        yarn.scheduler.capacity.queue-mappings=u:%user:%primary_group                       

                        If user name is same as queue name then

                        yarn.scheduler.capacity.queue-mappings=u:%user:%user                       

               Enable queue mapping override:

                            yarn.scheduler.capacity.queue-mappings-override.enable=true

                         Example:                    

                                  <property>

                                          <name>yarn.scheduler.capacity.queue-mappings</name>

                                          <value>u:njella:engineering, g:webadmins:weblog</value> 

                                  </proprty>

                                            

                                            If user "njella" explicitly submits an application to the marketing queue, the default queue assignment of engineering is overriden and the  application is submitted to the marketing queue.

                     

Issues

1. Ambari-agent



Sol : Change verify=platform_default   to verify=disable  in /etc/pythoncert-verification.cfg file

1. sed -i 's/verify=platform_default/verify=disable/' /etc/python/cert-verification.cfg

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How to Synchronize the system clock to Network Time Protocol (NTP) in Linux.

1.  If you do not have the ntpd service enabled use the below command to install and enable..

   a) yum install ntp.
   b) systemctl enable ntpd.

 

2. Modify the  /etc/ntp.conf  file as shown in the below image.  If you are using Cent OS 7, please modify the  cat /etc/ntp/step-tickers.

        You can also find the preferred ones for your location at http://www.pool.ntp.org/

3. Start the ntpd service

    systemctl restart ntpd

     

Configuring Network for CentOS Virtual Machine

1.

2.

3 

4.  echo "192.168.40.10" namenode1.mysandbox.com >> /etc/hosts

5.  echo "nameserver 192.168.40.2">> /etc/resolv.conf

6. [root@localhost ~]# vi /etc/selinux/config

Cassandra cqlsh

1. cqlsh is a command line utility for issuing query statemets to cassandra or         altering schema's in cassandra.
                    install/bin/cqlsh

2. Some of the options that you can pass to the cqlsh command are                  

  
3. cqlsh has some commands that are not there in Cassandra Query Language
       Below are some such commands

4. Copying data to or from a specified table and csv file
       

5. Default keyspaces in Cassandra:
             a) system_traces
             b) system
          

6.  cqlsh commands and CQL commands