You're thinking about NAS storage devices. Some drives are HDDs, while others are SSDs. You must find a balance solution between drive speeds and cost. What technique will you use to compare drive speeds?

When some drives are solid state and others are mechanical, the only method to fully compare speed is to measure input/output operations per second (IOPS). Mechanical drives frequently use revolutions per minute (RPM), also known as spindle speed, to indicate how quickly they can access data. Because solid-state drives (SSDs) do not have moving parts, there is no spindle speed. IOPS is a better way to compare drive performance regardless of drive type, and the only way when they are not the same type of drive. Other things to consider are the expected lifespan of the drive and drive latency.