What is CrystalDiskMark?

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CrystalDiskMark is a part of software. It offers you to benchmark your solid state drive (hard drive). The aim of benchmarking is to ensure that your HDD or SSD is doing optimally. CrystalDiskMark is only available on Windows. It is able to be all major Windows Releases. Even, it works on Windows 10 Tech Preview.


CrystalDiskMark allows you to choose any drive which you want and do lots of tests on them to measure achievement for reading and writing. It is going to run sequential read and write tests as well as random read and write tests. Also, it is going to display the results in MB/s and IOPS. For your information, you are able to download the latest version of CrystalDiskMark by clicking this link: http://crystalmark.info/software/CrystalDiskMark/index-e.html.

As you are going to see, there are five green buttons on the left hand side. Also, there are three boxes on the top of the UI that offer you to select the number of runs (For note: 3 is the default), the file size to use for the tests (1000MB by default) and the drive to run the tests on. Usually, running the tests three times is enough to get an accurate result. Aside from that, a file size of 1GB is also a good starting point. Therefore, we do not really suggest you mess with them too much if you only want a nice and fast idea of your HDD or SSD performance.

  • All
  • Seq
  • 512K
  • 4K
  • 4K QD 32

When you click on All, then all of the tests are going to be run. Also, you are able to run a single test by clicking on a specific button. For instance if you only want to test out random 4K read and write, simply you are able to click on 4K and then skip the other tests. Remember that running all tests will be able to take up to fifteen minutes or more if you have extremely slow disks.

In some cases, CrystalDiskMark is a stress test. So, if you have a drive which is failing already and you run a ton of I/O tests on that drive it can die on you in a hurry. Alternatively, CrystalDiskMark is safe to run in most cases. We use it every time we get a new SSD to test out performance and compare the results online to ensure the drive is on par for performance.

Based on the research, an IOP (I/O operation) brings several amounts of CPU time to allow the operating system and the hard drive to send or retrieve data from one another. Due to there is a performance cost for every IOP (I/O operation) that happens, so the idea is to send more data every trip, that reduces the amount of interactions which require to happen. Apparently, every operating system has its own default block size (Allocation size) that sets the amount of data it is able to fit into one block, or chunk, or whatever you wish to call it. Frequently the block size is 4KB to prevent massive storage space waste. If you determine the block size to 1MB you have to use up 1MB to store a single 1KB text file, that is clearly a waste of empty space. Usually, larger block sizes produce higher transfer rates and are measured in MegaBytes per second (MB/s). While smaller block sizes produce lower rates and are generally measured in I/O Operations Per Second (IOPS).


The CrystalDiskMark sequential tests are constantly the ones with the highest results. However, they are not constantly representative of the real world action. An instance of a streaming read will be when you watch a video on your computer, all of the data is located in one file, therefore it is easy to quickly read it. Once you copy a file, you are doing sequential reads and writes. We trust that CrystalMark is using 1MB file block size for this test.

For example: You are using a PNY 240GB SSD on Windows 8.1 Pro and CrystalDiskMark 3.0.3 x64. The PNY 240GB SSD gets approximately 336 MB/s for reads and 223 MB/s for writes. We think that it is not too bad, especially considering the price. It lasted over two years.  You may notice those numbers are not as high as NewEgg/ Amazon display. However, it is normal for an SSD. The more it fills up, so the slower it gets.


Many people said that CrystalDiskMark’s 512K test seems kind of redundant to them. Actually, the results were nice close to the sequential tests and we feel that the 4K test is the most useful test to run. For whatever reason, I/O Operations Per Second (IOPS) is not displayed at all. Even, if you hover over the results.


If you stick around over the MB/S bubbles in the middle, you are able to see the IOPS result, that must be shown by default really. Apparently, this CrystalDiskMark 4K test is not as demanding as the QD 32 test. It only uses a single thread, or queue to access data from your drive. SSDs are going to perform much better than HDDs as SSDs do not have to physically move stuff around to access data. Therefore, many small accesses located all over the place will be able to cripple a normal HDD. Trust us, if you do not have an SSD, you are extremely in need to get one.


The tests are utilizing 4KB file sizes. Your computer will be able to do many things in a hurry. However, it cannot do 32 things at the exact same point in time. Therefore, it uses queues and buffers to keep track of requests which still require to take place. For your information, each of those queued requests only takes an extremely small fraction of a second to complete. So, you are able to perform lots of operations in a second of time. If you are able to perform a write operation in say, 0.10 seconds, you will be able to say that you can perform 10 IOPS for random writes.

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