How to choose a storage?

Hi!

I am going to set up an oracle clustering system with two nodes and storage. I already succeeded it in virtual environment - nodes  and a storage(openfiler) in vmware. At the moment I have two Dell PowerEdge R710 servers , which can be used for nodes. But I can't decide which storage I should buy because of lots of shop lists and the compatibility with R710 servers. The amount of data which would be stored in the storage is 4 or 5 TB and I am searching for fast and medium price. Please anyone inform me which storage I can choose.