When setting up storage for ESXi hosts, before creating VMFS datastores, you must decide on the number and size of LUNS to provision. You can experiment using the adaptive scheme.
- Provision a large LUN (RAID 1+0 or RAID 5), with write caching enabled.
- Create a VMFS on that LUN.
- Create four or five virtual disks on the VMFS.
- 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, large LUN, possibly with a different RAID level, and repeat the process. Use migration so that you do not lose virtual machines data when you recreate the LUN.