Random I/O Operations per Second (IOPS) refers to the speed at which a drive can read and write random access patterns (as opposed to sequential access patterns). Solid state drives generally have much faster IOPS than traditional hard drives because SSDs can directly access the data on flash memory rather than needing to move the read and write heads and wait for the disk to spin underneath them.
* Performance measured using Iometer with queue depth set to 32; measurements are performed on 8 GB of Logical Block Address (LBA) range. Write Cache enabled. 4 KBs equals 4,096 bytes.