Oracle Database Discussions

Oracle 11g R2 on SUSE Linux 11 to support a public web site. There are two options for disk allocation:

1) Both the Operating System and the Oracle Software are installed on the same disk.

2) Install the OS and Oracle Software on two separate disks?

I kind of imagine the option 1 may cause the disk contention, but will save one disk for data storage; while
option 2 will be for efficient for I/O but use one extra disk.

I remember someone mentioned that for such a system, since the most of the kernel files will be loaded into the RAM, having both the OS and Oracle DBMS on the same disk won't cause the disk contention.

Like to hear your opinion.

Thanks