Many arrays provide a caching mechanism using memory or SSD disks to increase the number of IOPS the array can deliver. This allows a few slow drives to deliver a higher number of IOPS. This caching can greatly reduce the number of drives needed to deliver the same number of IOPS by writing to a faster cache instead of writing directly to disks. Fast cache of EMC and flash cache of NetApp are examples of vendor-specific SSD caching technologies that can be used to increase storage IO performance.