Hi Friend,
You need to first consider boot from SAN requirements:
Plz refer:
1.VMware vSphere 4 ESXi Installable and vCenter Server Documentation Center
2. VMware vSphere 4 - ESX and vCenter Server
3.https://www.youtube.com/watch?v=iUkCQPkn1Tk
The boot LUN must be dedicated to a single server. Hence you require dedicated LUN for each ESXi. (Total 10)
Let me know if you have any other doubts.