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From Sumit Mohanty <>
Subject Re: Multiple CentOS versions in same stack?
Date Thu, 14 Jan 2016 14:54:53 GMT
As far as I remember, when installing a cluster you can choose a cluster with mixed OS. Ambari
can pick the correct repo based on the OS. However, as Greg said, for an installed cluster
it may be a different issue. In general, centos6 and centos7 repo contents are compatible
but I am not 100% sure.

One path to try is to do an Add Host with centos7. I expect Add Host to pick the right repo
URL based on the OS. If you must use local repo then you need to edit the already stored repo
details in the DB to make sure that centos7/rhel7 one is pointing to your local centos7 repo.
If the above works as expected then you can try Remove Host/Upgrade/Add Host for the Slave
nodes. Its just that you need to remember what components are deployed on the host and add
those back. 

For master services, Remove/Add hosts do not work well especially for NameNodes. But NameNode
can be moved.

Another option is to Add a Slave host with CentOS6 and then upgrade and see what more is needed
to get that to work. If this option works for you then it might be the fastest way to upgrade
the OS. Assuming no binary issue, this option may require modifying CentOS7 repo to be the
same as the CentOS6 repo in the Ambari DB and repoinfo.xml files. 

>> Your best option is probably to spin up a new cluster with the new OS and migrate
the data.
+1 to this option
From: Greg Hill <greg.hill@RACKSPACE.COM>
Sent: Thursday, January 14, 2016 6:37 AM
Subject: Re: Multiple CentOS versions in same stack?

Honestly, I don't know that anyone has ever tried, but I have a feeling it
might not work out well.  The 'repo' is specified at the stack level, so
you'd have to make a new cluster after modifying the repo url on the stack
in order for the new nodes to even know to use a different repo from the
old nodes for installing packages.  Also, the os_family and os_type is in
the ambari-server configs and isn't overrideable per-node, unless there's
some hidden feature I'm not aware of.

Your best option is probably to spin up a new cluster with the new OS and
migrate the data.


On 1/13/16, 6:20 PM, "Andrew Robertson" <> wrote:

>Has anyone ever tried to run an Ambari cluster with hosts at different
>centos versions (or some nodes with one OS like centos and other nodes
>with something else?)
>Any reason this wouldn't be advised?
>I'm considering upgrading from centos 6 -> centos 7.  Given the
>current centos 6 -> 7 upgrade path is "reinstall", this make take some
>time to accomplish and I'd end up with a mix of both machine types in
>the cluster during this time.
>I don't see any reasons this would not work - but I also don't see
>anything that explicitly states this is a tested/advised config

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