I have a HP Proliant DL380 G4 and will be attaching a HP StorageWorks MSA20 Storage Shelf with SATA drives using a SMART ARRAY 6402/128.
Question: If I install ESXi 3.5 can I format the disks in the MSA20 as a VMFS datastore?
This all depends on your controller. If your controller is supported, then yes, you can create a VMFS on those disks. If the controller is not supported, then those disks will not be visible to ESXi.