rhel-recommended-partition-sizes.txt

From: http://www.redhat.com/magazine/022aug06/features/webserver
You can select automatic partitioning for your hard drive space, but it may not be ideal for this kind of deployment. Here is a suggested breakdown of your partitions, based on a computer with 1GB of RAM and a 160GB hard drive:

/boot     100MB 
/         10240MB
swap      2048MB  (this should  be twice the system memory)
/tmp      5120MB
/var      133120MB  (this is where the majority of your web content will be stored)
/var/log  10240MB