Redhat provides instructions for upgrading from RHEL 6 to 7 here:
https://access.redhat.com/solutions/637583
When carrying them out, I would recommend to follow the order and additional instructions in the "Zero-downtime upgrade" section of the Install guide.
However, it would be useful to get some input from those members of the community who have done this kind of upgrade on what they would recommend.
Many thanks!
There are no problems with the upgrade itself. Only problem we faced is the ordering in which all the components had to be brought up. As long as you have these documented or upgrade in a staggered fashion, you should be good.