What operating systems are certified for Oracle 11gr2 RAC? How can this information be found?
My Oracle Support has a certify tab which lists current certifications, including the one you are looking for. Here is how:


Select "Oracle Database" as the Product.
Select the release "11.2.0.1".
Click the link "Check certifications with another product.
Select the "Product Category" radio button.
In the Category drop down select "Operating Systems".