is it possible mix different RHEL OS version in HDP cluster?

[#1]

hi all

we are using the following HDP cluster with ambari ,

list of nodes and their RHEL version

3 masters machines ( with namenode & resource manager ) , installed on RHEL 7.2

312 DATA-NODES machines , installed on RHEL 7.2

5 kafka machines , installed on RHEL 7.2

now we want to add the following machines to the cluster but with RHEL 7.5

85 DATA-NODES machines , should be installed on RHEL 7.5 version

2 kafka brokers machines , should be installed on RHEL 7.5 version

so my question is

can we mix in HDP cluster RHEL 7.2 with RHEL  7.5 version ?

[#2]

@mike_bronson7 

I would say NO from a technical perspective, too many things changed since RHEL 7.2 mixing Family OS's in the same major release RHEL 7.2 and CentOS 7.5 is possible but while less likely, even that could lead to issues as it isn't tested. You'll want to pay close attention to versions of java, yum, python, etc on each node. You might have to edit the /usr/lib/python2.6/site-packages/ambari_server/os_type_check.sh to bypass some incompatibility and you will need to take care of the Kafka conflicts too are they the same versions??

Don't be afraid the fresh installation and configuration takes less time than fixing dependency problems and other issues but the better option is a rolling upgrade to the higher version 7.5

Between RHEL 7.5 and 7.2 you skip two releases not to speak about the jump from GNOME 3.14 to GNOME 3.26, in case the version Server with GUI is in use. Even if (only) upgrading from RHEL 7.2 to RHEL 7.4 - this is something where several problems are possible I think both ways have pros and cons.

Take precautions to avoid accidental updates by using an internal repo like Red Hat Satellite Server for content and configuration management hence protecting any necessary configurations, data, and attempt the yum update. You can do an echo n | yum update to see if it generates any yum errors.

In your case, it would good to upgrade to 7.7 and to avoid getting accidental 7.7 What you can do is to create a local repository that contains the packages from the RHEL 7.5 release and perform an offline upgrade to that edition, but you should disable the network in this case. Otherwise (when you run an online update) yum will pull in the latest stable packages ... which actually are from the current RHEL 7.7 release. 🙂

Solution to upgrade to 7.5

Execute the following command:         subscription-manager release --set=7.5
Clean up everything :                                   sudo yum clean all | sudo rm -r /var/cache/yum
Update the software sources:                sudo yum update redhat-release-server

On the HDP version, 2.5.x to 3.1.x and Ambari 2.5.x to 2.7.x can run without issues on RHEL 7.2 but RHEL 7.5 can only run HDP 2.6.0 to 2.1.4 and Ambari 2.6.2 to 2.7.4

[#3]

hi Shelton

you mention to upgrade to version 7.7

but https://supportmatrix.hortonworks.com/ , when you click on 7.7 , we not see any selected HDP or ambari

so I gues you means to upgrade to 7.6 version ( because 7.7 not approved for any HDP )

[#4]

@mike_bronson7 

it was a typo error I should have proofread again

"In your case, it would good to upgrade to 7.7 and to avoid getting accidental 7.7"  should read In your case, it would good to upgrade to 7.5 and to avoid getting accidental 7.7  this should match the highest version in your cluster  else when you run system update this will automatically upgrade to the latest stable version 7.7 that why you should use the internal repo or set  subscription-manager release --set=7.5

NB. Upgrading to 7.6 as you said would mean a lot of upgrade work for  both clusters 

Happy hadooping

[#5]

so lets summary to avoid mistake

rhel 7.7 can support HDP 2.6.4 and up ( latet HDP version )

rhel 7.7 can support 2.6.2.2 , 2.7.3 , 2.7.4  ambari version 

is it correct until now?

second

when current rhel version is 7.2 and we want to add rhel 7.7 OS version 

then its fully recommended to upgrade 7.2 to 7.7

is it correct ?

[#6 · Accepted solution]

@mike_bronson7 

I thought it was very clear that RHEL 7.7  is not supported as yet by HDP and I doubt whether it will as you well know development has been stopped in that line in prefernce for CDP !!

I didn't mention anywhere to upgrade to 7.7, I tried to correct the typo by trying to elaborate. Your current  Cluster OS versions are 7.2 and 7.5 so the best you can do is upgrade all to 7.5 after testing the procedure of course.

On a Linux box if you run the yum update command the yum downloads the latest stable release from the official repo, so to avoid accidentally upgrading to 7.7 which yum update will do  you should tell yum what OS version you what by following the steps below or use a satellite server which  controls the OS  version

Solution to upgrade to 7.5

Execute the following command:                          subscription-manager release --set=7.5
Clean up everything :                                                    sudo yum clean all | sudo rm -r /var/cache/yum
Update the software sources:                                 sudo yum update redhat-release-server

So forget about 7.7 that won't work out and Support matrix shows that , I hope I am now clear 🙂

[#7]

ok

so after second thinking I think its better to use the latest version that supported - 7.6 instead of 7.5

rhel 7.6 can support HDP 2.6.4 and up ( latest HDP version )

rhel 7.6 can support 2.6.2.2 , 2.7.3 , 2.7.4  ambari version 

and

when current rhel version is 7.2 and we want to add rhel 7.6 OS version 

then its fully recommended to upgrade 7.2 to 7.6