ReadSpeed is the most accurate benchmark of PC mass storage ever created. It has measurement stability and repeatability of greater than 4 significant digits – better than 1 part in 10,000, or 0.01%.

After you use ReadSpeed on your own system, you may have questions such as: Why is the end of my spinning hard drive half the speed of the front? Why does the end of my SMR-formatted drive show impossibly high performance? Why is the front of my SSD so much slower than the rest and why are there places where it virtually stalls? Are these problems? Should I worry? Is it possible to fix these things?

GRC provides public web forums to provide answers to all of the questions you are going to have. And it's a place to ask questions that haven't yet been answered. It is a community which includes many of the people who helped develop and test ReadSpeed. So, they are knowledgeable and experienced users. The forums will help you create a bootable ReadSpeed USB thumb drive, boot it on most PCs, run ReadSpeed, and put its results into context. And you will be able to compare your results with everyone else's.

As you can see in ReadSpeed's output above:

• Drive 80 is a high-quality 250GB Samsung 860 EVO SSD. Look at the five regional performance measurements shown. Every one of them is exactly 274.1 megabytes/second, plus or minus zero! This is at least four decimal digits of benchmark accuracy.
• Drive 81, the SanDisk X300 256GB MSATA, is almost as stable. It is slower and its performance is a bit less rock solid, but even so, each of the five regions is either 182.5 or 182.6. So we're measuring +/- 0.5 accuracy.
• But look at drive 82! Something is very wrong at the front of this drive. It's also a 256GB SATA SSD, but it's an off-brand “addlink” drive removed from a reconditioned Dell laptop. This drive reveals what most users of the benchmark have seen from their own highly used SSDs. The four regions at 25%, 50%, 75% and 100% are measuring 174.7 to 175.0, so still very stable. But the front of the drive is measuring only 46.2 mb/sec! When you watch this benchmark run (see the video below) you will see the progress bar stall while the SSD struggles to read some regions that are clearly having serious trouble. It ends up succeeding, but something is very wrong.
• Drives 83 and 84 are old “spinners” – Maxtor spinning hard drives. The benchmark reveals that hard drives are faster at their front and show successively slower performance as we move to the end of the drive. This is due to the inner tracks having a smaller circumference and therefore storing fewer bits.
• The other remarkably interesting thing to observe is the 25% region of the last drive, it's a brand new, never used, 2TB Seagate Barracuda that was taken out of its factory sealed bag and plugged in for the first time for this benchmark. During the benchmark, you can see the progress bar hiccup in the 25% region. Something is wrong there, and this brand new drive has never been used!

When we started out, we never imagined that we would be creating something so useful and surprising. The Benchmark was created as a platform to develop and test the new “Bare Metal” low-level hardware drivers being incorporated into the next release of SpinRite (v6.1). With the release of ReadSpeed, that goal has been achieved. SpinRite will soon be inheriting ReadSpeed's insanely fast drivers.

This benchmark provides new, ultra-high-performance drivers for IDE, SATA and eSATA drives connected to IDE (legacy) and AHCI (modern) PCI motherboard and add-on controllers. As soon as this technology has been added to SpinRite, work will begin on similar drivers for NVMe and USB controllers and their drives.

Like SpinRite, ReadSpeed is an old school (very old school) DOS program. Although this means that it can be a royal pain to run ReadSpeed, the only way to achieve ReadSpeed's accuracy is to run it in a bare minimum operating system such as DOS. Any modern operating system like Windows, Linux or macOS has far too much going on and generates far too much timing noise to enable super-accurate timing measurements.

Since no one uses DOS anymore, we have made it as easy as possible to succeed with something you've never done. “ReadSpeed for Windows” is our Windows app. After it is started, it watches while you insert any USB thumb drive you wish to wipe and setup to boot DOS and run ReadSpeed. ReadSpeed for Windows handles all the preparation work. It reformats any removable USB drive, installs the FreeDOS operating system, and adds a collection of DOS programs including the DOS RS.EXE benchmarking program that was shown running in the video above.

The trickiest part is getting a computer to boot from your USB drive, rather than from its regular, built-in mass storage drive. Although every computer provides some way to do this, there is no standard. Dell machines use the F12 key, pressed just after the “Dell” logo appears. Other systems briefly flash instructions on the screen when they are starting; sometimes it's F10, sometimes the “Del” key – it's a mess. But since this problem is quite common, the Internet will have the answer. Search for “how do I boot from USB on my {make & model of computer}” and you will find the answer. Sometimes more than one answer. Sometimes different answers. But one of them will work. And if all else fails, the GRC forums are waiting for you.

Recent laptops, and some desktops, may also be configured for “Secure Boot” which helps protect the machine from boot malware. Secure boot must be temporarily turned off when booting from USB.

The benchmark displays its results on the screen and also logs them to the USB drive. So, once you have used the benchmark under DOS, you can reboot your system normally and you will find the results in a file on the USB drive. Then, head over to GRC's forums where you will find a ReadSpeed forum for discussion of the benchmark and its results.

This is the file most users will want. It's an easy-to-run Windows program that will prepare any USB stick (of at least 4 megabytes) for booting BIOS-based machines to DOS and running the DOS ReadSpeed benchmark.

File stats for: ReadSpeed    Last Updated: Size: 383k Dec 24, 2020 at 20:01 (1,387.27 days ago) Downloads/day: 10 Total downloads: 23,770 Current Rank: 16 Historical Rank: 34

Linux and macOS users, who do not have access to Windows, may download the ReadSpeed IMG file. After unzipping, the Linux 'dd' command, or other image writing utility, can be used to write the filesystem image to any USB stick to create a bootable 8MB DOS filesystem:

File stats for: ReadSpeed for DOS (img)    Last Updated: Size: 345k Dec 26, 2020 at 12:56 (1,385.56 days ago) Downloads/day: 3 Total downloads: 6,615 Current Rank: 25 Historical Rank: 38

Anyone who already has a bootable DOS environment can simply add the ReadSpeed DOS executable – RS.EXE – and run the program like any DOS utility.

File stats for: ReadSpeed for DOS (zip)    Last Updated: Size: 19k Dec 26, 2020 at 12:59 (1,385.56 days ago) Downloads/day: 4 Total downloads: 4,540 Current Rank: 22 Historical Rank: 39

Release history:

• 2020-12-24 – Initial Christmas Eve release.