IOPS
also: I/O operations per second, input/output operations per second
IOPS (Input/Output Operations Per Second) is a measurement of how many read and write operations a storage device can perform in one second, indicating its speed and performance capacity.
IOPS quantifies storage device throughput by counting discrete input/output operations rather than data volume. A single operation might read or write a small block of data (typically 4KB), so IOPS focuses on operation frequency rather than megabytes transferred.
This metric is particularly important for workloads that involve many small, random access patterns—such as databases, virtual machines, or web applications handling concurrent requests. For example, an SSD might achieve 100,000 IOPS while a traditional spinning hard drive manages only 200 IOPS, reflecting the dramatic performance difference.
IOPS is often paired with latency (response time) and throughput (total data transferred) to fully characterize storage performance. You'll encounter IOPS when benchmarking disks with tools like fio or ioping, and cloud providers (AWS, Azure, etc.) rate their storage volumes by guaranteed IOPS levels.