The first thing, let check your RedHat Enterprise 6.3 and prepare environment for ready to installation Oracle Database 11g.
Minimum Ram: 1 GB
Minimum Swop: 1.5 Times of Ram (Recommend 2) in case of Ram 512 GB - 1GB
Minimum Disk Space:
/tmp require 150 - 200 MB (Recommend 400 MB)
Oracle Software Partition Requirement: 1.5 - 3.5 GB
Data Files Partition: 1.5 - 2 GB
Minimum Requirement Redhat Package for Oracle Database 11g. (It included in your installation DVD.)
