You see not all RHEL 6.x programs will run without porting on 7. If that's your situation, don't worry, be happy. Red Hat has just announced the release of RHEL 6.6.
I can sum up RHEL 6.6 in one phrase: some RHEL 7 features have been back-ported to RHEL 6.6.
The three main areas of improvement are in performance, system administration and virtualization.
First, RHEL 6.6's performance has been optimized. The operating system can now support up to 4,096 x86-64 processor cores, 64 terabytes of RAM, and 8 exabytes of storage. Red Hat also claims that it can do a much better job of accommodating dense single-server workloads.
The network stack has also been improved. Besides supporting more 40 GbE network adapters, it also features reductions in network latency and jitter, and support for high performance and low latency applications.
Last, but never least, in a world where virtualized servers now outnumber physical servers, RHEL 6.6 has better virtual guest functionality. In particular, RHEL 6.6 will work well as a KVM guest on RHEL 7. This neatly gets around the problem of maintaining older RHEL 6 applications if you want to move the bulk of your servers to the leading edge Red Hat operating system.
In a press statement, Jim Totton, Red Hat's VP and general manager, Platform Business Unit, said:
"With the release of RHEL 6.6, we continue to refine the stable and secure RHEL 6 platform which provides a reliable foundation to mission-critical systems across industries and regions.Whether you’re operating on bare metal, building out your virtual infrastructure, or leveraging the open hybrid cloud, RHEL 6, with enhancements to virtualization, performance and system administration, continues to be an excellent choice for deploying and managing large and complex IT projects."
If I were still using RHEL 6.x, I'm not sure I'd see this as a "must" upgrade, but I would certainly consider it well worth taking the time to kick its tires to see if I could address my needs while planning for an eventual migration to RHEL 7.