MD3200i and VMFS5 and Virtual disk segment size

Hi

Im in the process for implement an MD3200i and im looking for someone who have experience with this kind of tasks.

As far i understand, (and reeading this: http://pubs.vmware.com/vsphere-50/index.jsp?topic=%2Fcom.vmware.vsphere.storage.doc_50%2FGUID-3A05795A-283F-4959-AD81-FAC61FD8D456.html ). The guest operating system in a vmware enviroment request for the data to the SAN via the HBA adapter in the ESX host.

My question, and if i am right, the chunk of data it will be the size of the formating operating system, im correct?

This is, if the guest OS ask for 4Kbytes of information, the: OS -> adapter -> SAN controller - > lun -> physical disk.

so which is the best segment size in disk group for a lun? This lun will store like 10 web servers, with thousands of files each, from 1k to 500Mbytes in size (very random I/O).

Im actually configured  a RAID 1+0 ( 8 15k 600GB drives ) but i dont know which segment size i must use for this.

Any suggestions?

Thank you in advance and excuse my english. ;-)