I've been asked to investigate adding extra memory (> 16gb) to a RHEL 4 server and moving to a huge mem kernel. The server is used for Oracle RAC.Is it just a case of installing the hugh mem kernel and booting into ? or is it more complex than that ?Any tips / gotcha's ? 
What are the Implications of moving to Huge mem kernel on RHEL4
linux;kernel;rhel;memory
I use a BIGMEM kernel on Debian squeeze. I've used a non-BIGMEM kernel before as well. I'm not aware of any issues or gotchas, and no changes to the system are necessary when switching between a BIGMEM and non-BIGMEM kernel. Of course, you only need to use a BIGMEM kernel if you are running a 32 bit kernel. If you have any specific concerns, mention them in the question.