fpausp
You need to use a hardware RAID card with support for 4 drives, or a RAID card built in to the motherboard. Be careful to choose a card supported by CentOS 5.x
Alternatively use 5 x 2TB Disks (in software RAID) on sme 8.
Not sure if sme 9/CentOS 6 supports >2TB/GPT, but you can easily download the sme9 beta 2 iso & try it out. Do some research on CentOS 6.x first.