When you plan how to set up your storage for your ESX/ESXi systems before you format LUNs with VMFS datastores, you must decide on the LUN size and number of LUNs to use. You can experiment using the adaptive scheme.
Procedure
1
Create a large LUN (RAID 1+0 or RAID 5), with write caching enabled.
2
Build a VMFS on that LUN.
3
Place four or five virtual disks on the VMFS.
4
Run the applications to determine whether disk performance is acceptable.
If performance is acceptable, you can place additional virtual disks on the VMFS. If performance is not acceptable, create a new, larger LUN, possibly with a different RAID level, and repeat the process. Use migration so that you do not lose virtual machines when you recreate the LUN.