IOPSn

IOPSn is a metric used in storage performance analysis to express normalized input/output operations per second across different devices and workload classes. The letter n in IOPSn denotes a particular workload scale or class, such as a specific block size, queue depth, or mix of read and write operations. The concept is intended to facilitate comparisons when raw IOPS vary due to device capacity, configuration, or workload profile.

Usage and standards: There is no universal standard for IOPSn, and definitions may differ among vendors and researchers. In practice, IOPSn is derived by measuring IOPS under a baseline workload and then applying a normalization factor that accounts for the chosen scale n. This allows side-by-side comparisons of devices under equivalent scaled conditions.

Calculation: A typical approach is to select a baseline workload (for example, a 4 KB random read/write mix at a fixed queue depth). The measured IOPS is divided by a normalization factor that depends on n and the workload characteristics, yielding IOPSn. Higher IOPSn values indicate better performance for that scaled class, assuming the workload is representative.

Limitations and interpretation: Because normalization factors differ, IOPSn is most meaningful when all devices are evaluated under the same IOPSn definition and workload class. It should be used alongside raw IOPS, latency, and throughput metrics to provide a complete picture of performance and to avoid misinterpretation.

See also: IOPS, benchmark, storage performance, queue depth, latency, throughput.