Physically, you want the drives in a box and cables connected. The 1U JBOD above would work, if "some" is at most 4 and your "Proliant G7" has four eSATA connectors. However, that requires something from the controller in G7 (of which I know nothing about).
Typically you would use a RAID-controller (or software RAID) to turn JBOD into storage volume. SAS cable rather than four eSATA between the boxes (real cheap ones would use USB). The next step in price is to have the RAID-controller in the storage box. You'd still need a cable: USB, SAS, Ethernet, or FibreChannel.
Apart from physical connection (but affecting you choices) is what the ESXI can do, how does it manage storage, etc. I assume that it is a commercial product and I've always been told that commercial solutions are so good due to you paying for support ...
