I am not going to show you a step by step guide on how to install Oracle RAC there are many documents on the internet that explain it better then I could. However I will point to the one I am fond of and it works very will if you want to build a cheap Oracle RAC environment to play around with, the instructions are simple and I have had no problems setting up, installing and configuring it.
To configure a Oracle RAC environment follow the instructions in the document Build your own Oracle RAC cluster on Oracle Enterprise Linux and ISCSI, there is also a newer version out using 11g. As I said the document is excellent, I used the hardware below and it cost me a little over £400 from EBay, alot cheaper than an Oracle course.
I did try and setup a RAC environment on VMWare on my laptop (I do have an old laptop) but it did not work very well, hence why I took the route above.
|Instance Node 1, 2 and 3||
3 X Compaq Evo D510 PC's
|Openfiler Server||Compaq Evo D510 PC
CPU - 2.4GHz (P4)
RAM - 2GB
HD - 40GB
HD - 250GB (brought additional disk for ISCSI storage, more than enough for me)
|Router/Switch||2 x Netgear GS608 8 port Gigabit switches (one for the private RAC network, one for the ISCSI network (data))
Note: I could have connect it all to one switch and saved a bit of money
|Miscellaneous||1GB Network cards - support jumbo frames (may or may not be required any more) and TOE (TCP offload engine)
Network cables - cat5e
KVM switch - cheap one
Make sure you give yourself a couple of days to setup, install and configure the RAC, take your time and make notes, I have now setup and reinstalled so many times that I can do in a day.
Make use of that third node, don't install it with the original configuration, add it afterwards, use this node to remove a node from the cluster and also to simulate node failures, this is the only way to learn, keep repeating certain situations until you fully understand how RAC works.