Wednesday, May 28, 2014

Multi-Node Hadoop Cluster on Oracle Solaris 11 using Zones

This tutorial demonstrates how to setup an Apache Hadoop 1.2.1 Cluster using Oracle Solaris 11.1 Virtualization Technology or Zones.
I am running this setup inside Oracle VM VirtualBox 4.3.10 on Ubuntu 12.04 and the guest machine is running Oracle Solaris 11. Namenode will run inside Global Zone whereas we will be configuring 4 guest zones with almost same configuration for separate “Secondary Namenode” and 2 datanodes respectively.

LAB SETUP
Nodename
Zone
Hostname
IP-Address
Namenode
Global Zone
nn
10.0.2.15
Secondary Namenode
Guest Zone
nn2
10.0.2.16
Datanode1
Guest Zone
dn1
10.0.2.17
Datanode2
Guest Zone
dn2
10.0.2.18





NOTE: There are a few configurations that are needed to be done in all nodes as required. So I will show for a single node as the commands and steps will be same for all other nodes.

HADOOP USER & GROUP CONFIGURATION
Solaris installed inside a machine is in itself a “Global Zone”. So we have a global zone and say you had created a “user” user. Though we can use the same user to setup our Hadoop cluster but we will use a distinctive user named “huser” to perform our hadoop tasks more clearly.

Creating hadoop group
user$ sudo groupadd hadoop

Creating a hadoop user “huser” and place the user in hadoop group
user$ sudo useradd -m -d /export/home/huser -g hadoop huser

Setting the password for the user “huser”
user$ sudo passwd huser

By default, Oracle Solaris 11.1 does not create users with sudo permissions. Hence we need to assign “huser” user sudo permissions.
user@nn:~$ sudo vi /etc/sudoers
huser ALL=(ALL:ALL) ALL

After adding the user we continue our configurations using “huser” logins.
user@nn:~$ su – huser

NOTE: User and group creation, and configuring sudo permissions is done on the Global Zone which will be configured as namenode. The same will be done again on other zones also after we configure secondary namenode and datanodes zones separately.

HADOOP INSTALLATION ON GLOBAL ZONE (NAMENODE)
huser@nn:~$ sudo mkdir -p /usr/local/
huser@nn:~$ sudo chown -R huser:hadoop /usr/local/
huser@nn:~$ sudo tar -xzvf /tmp/hadoop-1.2.1.tar.gz
huser@nn:~$ sudo mv /tmp/hadoop-1.2.1 /usr/local/hadoop

NOTE: Hadoop installation is done only on namenode because in Oracle Solaris 11 Zones we have a facility to mount and share the data that is same across different zones. Hence it is important to install hadoop before we go for secondary namenode and datanode zones configuration.

CREATING A LOCAL REPOSITORY

ZONES CONFIGURATION
Creating virtual network interfaces for each zone
huser@nn:~$ sudo dladm create-vnic -l net0 nn2
huser@nn:~$ sudo dladm create-vnic -l net0 dn1
huser@nn:~$ sudo dladm create-vnic -l net0 dn2

huser@nn:~$ dladm show-link


Next we will create a zfs dataset for all zones.
huser@nn:~$ sudo zfs create -o mountpoint=/zonefs rpool/zonefs

NOTE: The zfs dataset for zones should not be rpool/ROOT dataset or immediately under the global zone filesystem root ("/") dataset.

Creating secondary namenode zone
huser@nn:~$ sudo zonecfg -z nn2
Use 'create' to begin configuring a new zone.
zonecfg:nn2> create
create: Using system default template 'SYSdefault'
zonecfg:nn2> set autoboot=true
zonecfg:nn2> set zonepath=/zonefs/nn2
zonecfg:nn2> add fs
zonecfg:nn2:fs> set dir=/usr/local/hadoop
zonecfg:nn2:fs> set special=/usr/local/hadoop
zonecfg:nn2:fs> set type=lofs
zonecfg:nn2:fs> set options=[ro,nodevices]
zonecfg:nn2:fs> end
zonecfg:nn2> add net
zonecfg:nn2:net> set physical=nn2
zonecfg:nn2:net> end
zonecfg:nn2> verify
zonecfg:nn2> commit
zonecfg:nn2> exit

Creating datanode zones
huser@nn:~$ sudo zonecfg -z dn1
Use 'create' to begin configuring a new zone.
zonecfg:dn1> create
create: Using system default template 'SYSdefault'
zonecfg:dn1> set autoboot=true
zonecfg:dn1> set zonepath=/zonefs/dn1
zonecfg:dn1> add fs
zonecfg:dn1:fs> set dir=/usr/local/hadoop
zonecfg:dn1:fs> set special=/usr/local/hadoop
zonecfg:dn1:fs> set type=lofs
zonecfg:dn1:fs> set options=[ro,nodevices]
zonecfg:dn1:fs> end
zonecfg:dn1> add net
zonecfg:dn1:net> set physical=dn1
zonecfg:dn1:net> end
zonecfg:dn1> verify
zonecfg:dn1> commit
zonecfg:dn1> exit

huser@nn:~$ sudo zonecfg -z dn2
Use 'create' to begin configuring a new zone.
zonecfg:dn2> create
create: Using system default template 'SYSdefault'
zonecfg:dn2> set autoboot=true
zonecfg:dn2> set zonepath=/zonefs/dn2
zonecfg:dn2> add fs
zonecfg:dn2:fs> set dir=/usr/local/hadoop
zonecfg:dn2:fs> set special=/usr/local/hadoop
zonecfg:dn2:fs> set type=lofs
zonecfg:dn2:fs> set options=[ro,nodevices]
zonecfg:dn2:fs> end
zonecfg:dn2> add net
zonecfg:dn2:net> set physical=dn2
zonecfg:dn2:net> end
zonecfg:dn2> verify
zonecfg:dn2> commit
zonecfg:dn2> exit

All the zones that are created can be listed using the below command.
huser@nn:~$ zoneadm list -cv


Installing zones
huser@nn:~$ sudo zoneadm -z nn2 install
huser@nn:~$ sudo zoneadm -z dn1 install
huser@nn:~$ sudo zoneadm -z dn2 install


It takes time to install the zones depending on your hardware setup.

We can see the list of all installed zones in the below screenshot.


Booting and configuring zones
huser@nn:~$ sudo zoneadm -z nn2 boot
huser@nn:~$ sudo zlogin -C nn2
huser@nn:~$ sudo zoneadm -z dn1 boot
huser@nn:~$ sudo zlogin -C dn1
huser@nn:~$ sudo zoneadm -z dn2 boot
huser@nn:~$ sudo zlogin -C dn2


NOTE: After executing the boot command, we can see the consoles of their respective zones using “zlogin” command. Here we will configure the system configurations as shown in the table for “Lab Setup”. Additionally, we will specify “user” user in user configuration screen without dns and authentication as we had configured global zone while installation. After the system configuration has been done, we will login as “user” user in all nodes.


Create "huser" user & "hadoop" group in all nodes as done earlier in global zone. If the installation & configuration is done differently than the global zone, then make sure that the "huser" user-id & hadoop group-id in datanodes is identical as in namenode.

HOSTS FILE CONFIGURATION
It is necessary to populate the hosts file all nodes with the ip addresses of all other nodes.


PASSWORDLESS SSH CONFIGURATION

OPENJDK 7 INSTALLATION
I will be using openjdk-7-jdk package which installs easily.
huser@nn:~$ sudo pkg install --accept developer/java/jdk-7


NOTE: OpenJDK installation has to be done on all nodes.

USER ENVIRONMENT CONFIGURATION
As we have already logged in as “huser” user we will edit the .bashrc file in the home directory of “huser” to set the user environment and paths.
huser@nn:~$ vi .bashrc


Execute the .bashrc file
huser@nn:~$ exec bash

NOTE: User environment has to be configured on all nodes to declare the essential variables for both java and hadoop mainly.

HADOOP CONFIGURATION
Here we will begin our hadoop configuration. All the configuration files are present in “/usr/local/hadoop/conf” directory

NOTE: All configurations have to be done only on namenode because we have already shared and mounted the global zone "/usr/local/hadoop" mountpoint onto all other guest zones.

Hadoop Environment - hadoop-env.sh
huser@nn:~$ vi /usr/local/hadoop/conf/hadoop-env.sh
export JAVA_HOME=/usr/java
export HADOOP_LOG_DIR=/var/log/hadoop-log

Create "hadoop-log" directory as specified in "HADOOP LOG DIR" variable in the hadoop-env.sh configuration file
huser@nn:~$ sudo mkdir /var/log/hadoop-log
huser@nn:~$ sudo chown -R huser:hadoop /var/log/hadoop-log


NOTE: /var/log/hadoop-log directory has to be created on all nodes with required “huser” user and group ownership and permissions.

Default Filesystem - core-site.xml
core-site.xml file which helps in pointing the datanodes to namenodes and which port they should listen to.
huser@nn:~$ vi /usr/local/hadoop/conf/core-site.xml


NOTE: We can use IP address or hostname and whichever port number of the namenode. Commonly used port number is 9000, but I have chosen 10001. “/tmp” directory has to be created only on namenode global zone.

MapReduce Framework – mapred-site.xml
This file used to point all the task-trackers to the job-tracker. The parameter: mapred.job.tracker sets the hostname or IP and port of job-tracker.
huser@nn:~$ vi /usr/local/hadoop/conf/mapred-site.xml


NOTE: Port number 10002 is my choice, it is not mandatory to use the same port number.

HDFS Configuration – hdfs-site.xml
File hdfs-site.xml contains various parmeters that configures HDFS.
huser@nn:~$ vi /usr/local/hadoop/conf/hdfs-site.xml


As specified in the hdfs-site.xml file, we need to create directories "hdfs" and "name" in namenode with appropriate “huser” user & group ownership.
Namenode Configuration
huser@nn:~$ sudo mkdir -p /hdfs/name
huser@nn:~$ sudo chown -R huser:hadoop /hdfs

All Datanodes Configuration
huser@dn1:~$ sudo mkdir /hdfs/data
huser@dn1:~$ sudo chown -R huser:hadoop /hdfs

NOTE: Repeat the datanodes configuration steps in all datanode zones.

conf/masters
The masters file contains the location where the secondary namenode daemon would start.
huser@nn:~$ vi /usr/local/hadoop/conf/masters
nn2

NOTE: We have configured separate machine for the secondary namenode hence we are defining secondary namenode explicitly here.

conf/slaves
The slaves file contains the list of datanodes where the datanode and task-tracker daemons will run.
huser@nn:~$ vi /usr/local/hadoop/conf/slaves
dn1
dn2
dn3

NOTE: The file should contain one entry per line. We can also mention “namenode” and “secondary namenode” hostname in this file if we want to run datanode and task-tracker daemons on “namenode” and “secondary namenode” too.

STARTING HADOOP CLUSTER
Formatting HDFS via namenode
Before we start our cluster we will format the HDFS via namenode. Formatting the namenode means to initialize the directory specified in “dfs.name.dir” and “dfs.data.dir” parameter in hdfs-site.xml file. After formatting the namenode, “current”, “image” and “previous.checkpoint” directories will be created on namenode and the data directory in datanodes will simply be formatted.

huser@nn1:~$ hadoop namenode -format

NOTE: We need to format the namenode only the first time we setup hadoop cluster. Formatting a running cluster will destroy all the existing data. After executing the format command, it will prompt for confirmation where we need to type “Y” as it is case-sensitive.

Starting the Multi-Node Hadoop Cluster
Starting a hadoop cluster can be done by a single command mentioned below.
huser@nn:~$ start-all.sh

This command will first start the HDFS daemons. The namenode daemon is started on namenode and datanode daemon is started on all datanodes. The secondary namenode daemon is also started on secondary namenode. In the second phase it will start theMapReduce daemons, job-tracker on namenode and task-trackers on datanodes.

Execute “jps” command on all nodes to see the java processes running,
NameNode and JobTracker” processes on namenode,
SecondaryNameNode” in seconday namenode zone and,
DataNode and TaskTracker” on datanode zones.


MONITORING HADOOP
Both HDFS and MapReduce provide Web-UI Management websites to browse the HDFS, monitor the logs and jobs.

HDFS: http://nn:50070
The DFSHealth site allows you to browse the HDFS, monitor namenode logs, view nodes, check the space used, etc.


MapReduce
Job-Tracker: http://nn:50030

The job-tracker site provides the information regarding running map and reduce tasks, running and completed jobs and much more.


Here we have completed creating a Multi-Node Hadoop Cluster using Oracle Solaris 11 Zones.

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