What Are IOPS and How Does it Differ Compared to Throughput


Ever wondered why your computer struggles with certain tasks? The answer might lie in a term called Input/output operations per second, or simply IOPS. In this blog post, we’ll demystify this often-overlooked but critical aspect of your device’s performance.

Definition and Concept of IOPS

Input/Output operations per second, is a critical measurement of the read and write speed of storage devices. This benchmarking unit applies to various storage solutions like solid-state drives (SSD), hard disk drives (HDD), and storage area networks (SAN).

It  helps users verify if a device’s speeds match up with what manufacturers claim.

Total IOPS include measurements such as random write IOPS, random read IOPS, sequential write IOPS, and sequential read IOPS. These different aspects allow an in-depth understanding of how your storage medium performs under varied workloads.

Variation may arise due to factors like internal controllers and latencies -making it essential to run detailed tests rather than relying solely on the manufacturer’s claims which often state optimum “up to” speeds that may not always reflect real-world performance.

Measuring IOPS

Benchmarking Tools

In the realm of understanding storage device speed, benchmarking tools play a fundamental role in measuring it. Tools such as Iometer and CrystalDiskMark are common examples of performance testing tools that provide detailed insights into read and write speeds.

  • Iometer: This open-source tool is favored for its comprehensive approach to testing and measuring the capability of storage devices. It records five key types of IOPS measurements – total IOPS, random write IOPS, random read IOPS, sequential write IOPS, and sequential read IOPS – providing a thorough outline of storage device performance parameters.
  • CrystalDiskMark: This is another widely-used tool that offers similar functionalities as Iometer. It collects data on both random and sequential operations to determine the overall performance. CrystalDiskMark can display results in MB/s or IOPS units, giving users flexibility on how they want their information represented.

Calculation Methods

Data storage devices’ read and write speed can be measured precisely using Input/Output operations per second, or IOPS. Various calculation methods provide a comprehensive understanding of their performance:

  1. Utilize performance metricsPerformance metrics are robust tools to analyze storage device speed.
  2. Deploy benchmarking tools: Software like the Iometer or CrystalDiskMark helps measure these parameters accurately. These measurement tools operate by generating and tracking input/output data packets under controlled conditions.
  3. Adopt a systematic calculation process: Begin with measuring random write and read speed. This involves writing and reading small blocks of data randomly across the device’s storage media.
  4. Proceed with sequential measurements: After random operations, evaluate the sequential write and read performance. In this method, large blocks of data are written or read in sequence onto the media.
  5. Interpret results correctly: Once you obtain raw data for these tests, it’s crucial to interpret them appropriately to understand their implications on the device’s speed and overall performance.
  6. Cross-check measurements from different devices: To get an accurate understanding of relative performance, do similar tests on different types of storage devices such as SSDs, HDDs, and SANs. Consider factors like internal controllers and latencies that could affect the results.

Interpreting Results

Interpreting the results of IOPS measurements is crucial for understanding the performance capabilities of your storage devices

These numbers represent the speed at which your storage device can handle input/output operations per second. By analyzing these results, you can determine how efficiently your device handles different types of workloads.

For example, if you are primarily working with large sequential files, a high sequential read/write IOPS would be beneficial. On the other hand, if your workload involves small random access files, focus on improving random read/write IOPS.

What is throughput?

Throughput is a crucial term in the world of storage performance. It refers to the amount of data that can be transferred over a given period. Essentially, throughput measures how fast data can flow through a storage device or system.

This metric is particularly important in scenarios where high data transfer rates are essential, such as streaming services and image hosting.

Unlike IOPS, which focuses on measuring input/output operations per second, throughput evaluates the overall capacity for transferring data efficiently. It provides an understanding of how quickly data can move through a storage system without necessarily taking into account the specific operations being performed.

Measuring throughput allows users to assess the efficiency and capabilities of their storage devices or systems by determining how much data they can handle within a specified timeframe.

By considering both IOPS and throughput metrics together, users can gain valuable insights into their storage performance and make informed decisions when selecting or evaluating storage solutions.

Limitations of IOPS

One of the limitations of it is that it may not fully represent real-world storage performance. While it provides a valuable measurement of read and write speeds, it does not take into account other factors that can affect overall storage performance.

For example, while high it’s readings might indicate fast random access times, sequential read or write speeds could be slower in reality.

Another limitation is that claimed IOPS values provided by manufacturers are often based on ideal testing conditions. In practice, the actual performance may vary depending on various factors such as workload type, file sizes, and data transfer patterns.

So, it’s important to consider these limitations when comparing storage devices based solely on their IOPS ratings.

Additionally, different types of storage devices like solid-state drives (SSD), hard disk drives (HDD), and storage area networks (SAN) can have varying degrees of latency and internal controllers which impact their measured IOPS values.

It’s crucial to understand these differences when evaluating the suitability of a particular technology for specific use cases or applications.

Ultimately, while it  offers insights into an aspect of storage device performance, one should also consider other metrics like throughput and real-world usage scenarios to gain a more comprehensive understanding before making informed decisions about purchasing and implementing storage solutions

Limitations of throughput

Throughput, which is the amount of data that can flow through a storage device, has its own set of limitations. One limitation is that it doesn’t provide a complete picture of the performance of a storage system.

While throughput measures the speed at which data flows, it doesn’t take into account factors like random or sequential read and write operations. Additionally, streaming services may prioritize throughput for continuous data flow but neglect other important aspects such as random access speed.

Another limitation is that throughput measurements don’t consider the physical storage capacity or total IOPS (Inputs/Outputs per Second), which are essential metrics in evaluating overall system performance.

It’s worth mentioning that measuring it provides a more accurate account of a storage device’s speed compared to relying solely on throughput. Therefore, understanding these limitations helps users make informed decisions when selecting and evaluating their storage devices for optimal performance.

Measuring throughput

Measuring the throughput of a storage device is crucial for understanding its performance capabilities. Here are some key points to consider:

  • Throughput measures the amount of data that can flow through a drive or system in a given period.
  • It is commonly used in streaming services, where consistent and high data transfer rates are necessary.
  • Throughput is measured in units such as megabytes per second (MB/s) or gigabits per second (Gb/s).
  • To measure throughput, specialized benchmarking tools like Iometer or CrystalDiskMark can be used.
  • These tools simulate real-world scenarios and provide accurate measurements of a storage device’s data transfer rate.
  • Measuring throughput helps ensure that the actual performance matches the manufacturer’s claims.
  • Real-world factors like file size, file types, and access patterns can affect the observed throughput.
  • It is important to take into account any limitations imposed by internal controllers or latency when interpreting throughput measurements.

Understanding the Difference Between IOPS and Throughput

IOPS vs. Data Transfer Rate

  • IOPS (Input/Output Operations Per Second) measures the number of read and write operations a storage device can perform in one second. It focuses on the speed and responsiveness of individual input/output operations.
  • Data transfer rate, on the other hand, refers to the amount of data that can be transferred within a given period. It represents how quickly data can flow through a storage device.
  • While both IOPS and data transfer rate are indicators of storage device performance, they measure different aspects. IOPS focuses on individual operations, providing insights into random or sequential access speeds. Data transfer rate, on the other hand, looks at overall throughput or the capacity for transferring large amounts of data.
  • IOPS is often used to evaluate performance in scenarios where random access speed is crucial, such as databases or virtual environments. It provides a more accurate representation of how quickly an application can process small-sized or random read/write requests.
  • Data transfer rate is commonly used in situations where continuous streaming or large-scale data transfers occur frequently. This metric is essential for applications like video editing or file backups that require high-speed data handling.
  • When evaluating storage devices, it’s important to consider both IOPS and data transfer rates since they serve different purposes. For example, while an SSD may have high IOPS for small-sized operations, its overall throughput might not be as impressive compared to a fast HDD.
  • Balancing IOPS and data transfer rate is key to optimizing performance based on your specific use case. Depending on your requirements, investing in devices with higher IOPS may be more beneficial than focusing solely on achieving maximum data transfer rates.

Balancing IOPS and Throughput for Optimal Performance

To achieve optimal performance from your storage devices, it’s crucial to find the right balance between IOPS and throughput. While IOPS measures the input/output speed of a device in terms of read and write operations per second, throughput focuses on the amount of data that can flow through the drive.

Finding this balance is essential because high IOPS may not necessarily translate into better overall performance if the throughput is low. On the other hand, if you prioritize high throughput at the expense of IOPS, it might result in slower response times for individual operations.

By considering both metrics together, you can ensure that your storage solution meets your specific needs. Whether you’re dealing with streaming data or random access patterns, striking a balance between IOPS and throughput will help you optimize performance and enhance productivity.

SSD vs HDD: A Comparison of IOPS

Solid State Drives (SSD)

Solid State Drives (SSDs) are a type of storage device that offers high-performance and faster data access compared to traditional Hard Disk Drives (HDDs). SSDs use flash memory technology, which means they have no moving parts, resulting in quicker read and write speeds.

One important metric for comparing the performance of SSDs is their Input/Output Operations Per Second (IOPS) measurement. IOPS measures how many input/output operations a drive can perform in one second, providing insights into its speed and responsiveness.

By understanding the IOPS capabilities of an SSD, users can make more informed decisions when selecting storage devices for their needs.

Hard Disk Drives (HDD)

A hard disk drive (HDD) is a traditional storage device that uses magnetism to store and retrieve data. It consists of spinning disks (platters) coated with a magnetic material, and reading/write heads that move over the surface of the platters.

HDDs are known for their large storage capacity and relatively lower cost compared to solid-state drives (SSDs). However, they have slower performance in terms of input/output operations per second (IOPS) due to mechanical limitations.

This means that accessing data from an HDD can take more time compared to an SSD. When considering the comparison between SSDs and HDDs in terms of IOPS, it becomes clear that SSDs offer significantly higher performance, making them ideal for applications requiring fast read/write speeds such as gaming or multimedia editing.

IOPS Comparison

Solid State Drives (SSDs) and Hard Disk Drives (HDDs) showcase varied IOPS measurements due to the differences in their technology. It’s essential to comprehend these variations when selecting a storage device. Below is a comparative analysis of SSD and HDD in terms of IOPS:


Storage Type Random Read IOPS Random Write IOPS Sequential Read IOPS Sequential Write IOPS
SSD Up to 100,000 Up to 90,000 Up to 20,000 Up to 20,000
HDD 500 – 900 400 – 800 150 – 200 150 – 200


SSDs attain up to 100,000 random read IOPS and up to 90,000 random write IOPS, demonstrating their superior performance. For sequential operations, SSDs offer up to 20,000 IOPS for both read and write operations. On the other hand, HDDs significantly lag with 500-900 IOPS for random reads, 400-800 IOPS for random writes, and a mere 150-200 IOPS for sequential reads and writes. Thus, SSDs provide considerably higher IOPS than HDDs, resulting in faster data access and superior overall performance. Understanding of these differences is crucial in selecting a storage device that best suits a user’s requirements.


In conclusion, IOPS (Input/Output operations per second) is a crucial measurement when it comes to understanding the performance capabilities of storage devices. Whether you’re using solid-state drives (SSD), hard disk drives (HDD), or storage area networks (SAN), knowing the it can help determine how fast your data can be read and written.

By measuring and analyzing it, users can optimize their storage systems for optimal performance and ensure they are getting the most out of their hardware investments.

I am a computer engineer holding a bachelor's degree in Computer Science, complemented by a Master's in Business Administration from University of Strathclyde, Scotland. I currently work as a Senior IT Consultant in Melbourne, Australia. With over 15 years of...