For those who are interested :
You must absolutely read the documentation on ASM, Grid Infrastructure and RAC.
I also recommend 3 books
1) Pro Oracle Database 11g RAC on Linux — by Steve Shaw and Martin Bach [Apress Publishing]
2) Oracle 11g R1/R2 Real Application Clusters Essentials — by Ben Prusinsky and Syed Jaffer Hussain [Packt Publishing]
2) Oracle 11g R1/R2 Real Application Clusters Handbook — by Ben Prusinsky, Guenad Jilveski and Syed Jaffer Husssain [Packt Publishing]
3) Oracle Database 11g Release 2 High Availability — by Scott Jesse, Bill Burton and Bryan Vongray [Oracle Press]
The 11gR2 Grid and RAC Accelerated training at Oracle University is also recommended but expensive.