VMware VMFS Datastore Sizing Calculator  
Total Number of VMs  Total IOPS per Lun  
Number of VMs in Single VMFS Datastore Read IOPS  
Total Disk Size for the VM (GB) Write IOPS  
Memory Assigned per VM (GB) Write IOPS w/Penal  
Total IOPS per VM Backend IOPs  
Read Ratio % Total Size of a Single VMFS Datastore(GB)  
Write Ratio % Total No. VMFS datastores  
Spindles Required for a Single Lun  
Disk RPM
Spindles Required for all the Luns