I took a look already at OS support matrix here:
And we would like to make some final decision regarding which OS to purchase (right now we are just using Scientific Linux 6.1, with tons of different libraries installed in order to make things work, we managed to make it working but there are still problems sometimes popping out).
For example we still have issues with QRC Menu loading, and i saw that some people suggest install RHEL5.5 to get rid of that problem.
So which one would you suggest to buy, RHEL6 or RHEL5?
I noticed for example that MMSIM11,12 do not work with RHEL6 accoding to that product matrix (however it works for us on Scientific Linux 6.1 which is RHEL6 clone).
So would the RHEL5 then be a nice option which would go on with most of even newer versions of IC design tool packages for at least more than some couple years? should we opt for RHEL5 now and go ahead buy it?
I've been using RHEL6 for some time now (about a year), with no problems (apart from a problem with IC615 prior to ISR12, when running 64 bit mode; officially RHEL6 was not supported until ISR12 though). Note that MMSIM11 and MMSM12 do support RHEL6 - if you look on the http://downloads.cadence.com page for each release, you'll see RHEL6 is listed; there's an error on the platform support page for these releases (I reported this recently, and it's supposed to be getting fixed).
IC615 ISR12 onwards supports RHEL6 too.