IO - IOPS (Input/Output Operations Per Second)

About

IOPS (Input/Output Operations Per Second, pronounced eye-ops) is a common performance measurement used to benchmark computer storage devices like:

• Local Storage: Hard Drive / disk (SSD, Platter, NVM)
• Remote Storage: storage area networks (SAN).

Parameters

The specific number of IOPS possible in any system configuration will vary greatly, depending upon the variables the tester enters into the program, including:

• the balance of read and write operations,
• the mix of sequential and random access patterns,
• the number of worker threads
• the queue depth (the number of outstanding IO),
• the buffer sizes of the application (??)
• the block of the file system.

Be careful, there are also a lot of other factors which can also affect the IOPS results including:

• the system setup,
• storage drivers,
• OS background operations,
• etc.

Formula

Sequential

The answer is typically converted to MegabytesPerSec

<MATH>IOPS = \frac{\text{Bytes Per Second}}{\text{Transfer Size In Bytes}}</MATH>

Random IO operations

<MATH> IOPS = \frac{1}{seek + latency} </MATH>

Raid

Drive - RAID Technology Overview

<MATH> IOPS = \frac{\text{Number of disks} * \text{Average I/O Operations on 1 disk per-sec}}{ \text{% of read workload} + (\text{Raid Factor} * \text{% of write workload})} </MATH> where:

• Number of disks: If one disk can perform 150 IOPS, two disks can perform 300 IOPS
• Raid Factor (ie RAID1,2, …)

Software

IOPS can be measured with applications, such as:

• Iometer
• IOzone
• and FIO

Documentation / Reference

• wiki/IOPS