I have built out a new virtual production environment (VMWare, HA enabled, VMotion... all the bells & whistles) using RHEL5 VM's.
I have got another ESX host that I plan to use as a pre-prod environment. To save some costs on RH subs I was thinking about installing this environment using CentOS. I believe it uses the same kerenl as RH?
Has anybody got any thoughts advise regarding this?
I would not do it. CentOS does not exactly match RHEL in many respects. I would want my pre-production environment to be exactly the same as my production system in order to ensure accurate testing of applications, etc.
I agree that your pre-production should as closely match production as possible. On the other hand I have worked on environments where just what you describe was done, the only "trick" we needed was adding a dummy /etc/redhat-release entry for oracle to install... We would occasionally run into various library and compat mismatches as well.