Input/output operations per second (IOPS) is the measure of how many input/output operations a storage device can complete within one second. It is a standard performance benchmark for hard drives, solid state drives, flash drives and even network attached storage (NAS) devices. Although IOPS is a common performance indicator, performance measures for the same device can vary from system to system based on other factors.
The most common performance characteristics that are measured are random and sequential operations. Sequential operations are generally related to access of stored operations in a contiguous way, usually associated with operations concerning large file sizes. Random operations, on the other hand, access locations in the storage device in a non-contiguous manner, which is related to small file sizes that are dispersed all over the storage medium.
There are the different characteristics that IOPS measures:
- Sequential Write IOPS: The average of the number of sequential write I/O operations that occur per second
- Sequential Read IOPS: The average of the number of sequential read I/O operations that occur per second
- Random Write IOPS: The average of the number of random write I/O operations that occur per second
- Random Read IOPS: The average of the number of random read I/O operations that occur per second
- Total IOPS: The total IOPS when performing mixed read and write operations
