CCAH - Administration

Hi @itversity @Sohail

While adding hosts to cluster in last step I can see below exceptions, is there anything to worry about.

The following failures were observed in checking hostnames. Showing first 1000 failures only…
DNS lookup of host goli003 on host goli004 failed. Expected but got

DNS reverse lookup of IP on host goli004 failed. Expected goli003 but got

Transparent Huge Page Compaction is enabled and can cause significant performance problems. Run “echo never > /sys/kernel/mm/transparent_hugepage/defrag” and “echo never > /sys/kernel/mm/transparent_hugepage/enabled” to disable this, and then add the same command to an init script such as /etc/rc.local so it will be set on system reboot. The following hosts are affected:

There are mismatched versions across the system, which will cause failures. See below for details on which hosts are running what versions of components.

Cloudera supports versions 1.6.0_31 and 1.7.0_55 of Oracle JVM and later. OpenJDK is not supported, and gcj is known to not work. Check the component version table below to identify hosts with unsupported versions of Java.

Java versions are inconsistent across the managed hosts. Check the component version below to identify hosts with inconsistent Java versions.

Hello @itversity @Sohail

Could you please advise me on these errors.


hosts should be in below format

10.x.x.1 FQDN host_name
10.x.x.2 FQDN host_name

  1. Run with sudo access echo never > /sys/kernel/mm/transparent_hugepage/enabled to disable

  2. Java versions are depending on which version of CDH you are choosing
    Ex: Its for CDH 5.8 refer Supported JDK versions


Thanks for the reply Krishna, in which files I need to update the hostname?

Also, please confirm the entry as well, should it be like this as suggested by you:

e.g: FQDN goli003

/etc/hosts goli003


i didn’t use in any of my nodes, is it mandatory.

will goli003 only not work ? is a example, you can use any other like

10.x.x.1 goli003

Is it mandatory: If you want to follow industry standards, yes it is mandatory

hostname and hostname -f should be same.


Yeah, I know this is for example, like I haven’t used anything after goli00[1-4] in any of my config files.

Even, i am able to open the apache page for goli00[1-4] and cloudera manager also.
What kind of issues I will face if not using .com?

You may face DNS related issues


Do I need to start from very first step or just an update in config files will work for me

You dont have to start from first. Just update /etc/hosts


what about file /etc/sysconfig/network.

Hi @krishnachaitanya

I have updated /etc/hosts and still got the same error:

DNS lookup of host on host failed. Expected but got
DNS reverse lookup of IP on host failed. Expected but got

Hi @krishnachaitanya

Thanks for the help, issue got resolved now :slight_smile: