If there’s one technology that has taken the storage world by storm over recent years, it’s flash drives. Solid State Disks (or SSDs) have transformed the storage landscape, offering much higher I/O density (IOPS per TB of storage) than can be achieved with traditional hard drives. HDDs are obviously mechanical media, based on spinning platters, accessed by multiple read/write heads. The physical geometry of these devices means that they are more attuned to sequential than random workloads. It’s easy, for example to write data sequentially onto a disk track as the disk rotates past the head. What’s much harder for HDDs is to manage random I/O profiles that read data from physically disjoint parts of the drive, either on separate tracks or platters. Totally random read requests can slow a hard drive down to 120-200 IOPS, depending on the drive speed.