Sequential read test for a hardware resale check

Before you sell a computer or external drive, you may want to show that it can read files at a reasonable speed. A slow result can also raise questions about a cable, port, connection, or the drive itself.

The Storage Test measures large-file disk speed and small writes in your browser. Use the large-file read result as one part of a repeatable check, not as a guarantee of the drive's health or a universal pass mark.

Test sequential read speed

Open the Storage Test on the computer and drive you plan to sell. Close file copies, downloads, and other tasks that may be using the drive.
If you are checking an external drive, connect it directly to the computer when possible. Use the same cable and port for each run, and avoid changing the setup midway through the check.
Start the test and let it finish. Review the large-file read result separately from the write result and small-write result. Record the number, the drive being tested, and how it was connected.
Run the test again after a short pause under the same conditions. If the readings are close, the result is more useful as a baseline than a single run. If they vary widely, note that too rather than choosing only the fastest number.

A sequential read test measures how quickly a drive can deliver a large, continuous block of data. That is useful for estimating tasks such as copying a large video file or opening large media assets. It is not the same as measuring small-file access, which can affect how responsive some everyday tasks feel.

What the result means

The read result is consistent across runs

Similar readings suggest the test conditions are reasonably stable. Keep the result with the device's sale notes, but describe it as a browser storage benchmark, not a certified drive speed. Results can differ from a manufacturer's advertised number because the browser, computer, interface, and test conditions all matter.

The read result is low compared with your own earlier run

First check whether anything changed: a different cable, port, hub, power state, browser, or background task can affect the result. A benchmark from another computer is not a direct comparison unless the rest of the setup is similar. There is no single browser-test number that proves a drive is good or bad across all models.

The read result looks fine, but the small-write result is low

Large-file reads and small writes measure different kinds of activity. A drive can deliver large blocks quickly while taking longer to handle many small operations. Keep those results separate, and avoid using the sequential read number alone to predict every part of the computer's responsiveness.

Results jump sharply between runs

Changing workload, temperature, caching, or a connection issue may be affecting the measurement. Repeat once with the computer idle and the same connection. If the variation remains, report the range or inconsistency rather than presenting one unusually high result.

How to get a more reliable result

Stop other disk activity. Pause large downloads, backups, and file copies before testing. A second task using the same drive can compete for its attention and make readings less repeatable.
Use a direct connection. If an external drive is connected through a hub or dock, try a direct port and compare. Keep the same cable and port for repeat runs so you are not comparing different connection paths.
Let the computer settle. After a large copy or a demanding task, wait a few minutes before testing. A warm drive or busy computer can behave differently from one that is idle and cool.
Keep the test environment consistent. Use the same browser and computer for before-and-after results. Close extra tabs and apps, and avoid comparing a private browsing session with a normal session as if the conditions were identical.
Check available space. A nearly full drive may behave differently from one with plenty of free space. Check the drive in File Explorer on Windows or Finder on macOS, and record its approximate free space with the result.
Repeat after reconnecting only if needed. If the result is unexpectedly slow, reconnect the drive securely and test again. Do not repeatedly run long tests just to chase a higher number. A few controlled readings are more useful than many runs with changing conditions.

When the drive may be faulty

A low sequential read result by itself does not show that a drive is failing. Look for stronger signs, such as the drive disconnecting, files failing to open, repeated read errors, or the same poor behavior on another computer with a known-good cable and port. Back up important files before troubleshooting further.

A browser benchmark cannot read a full health report or confirm how much life remains. It also cannot authenticate the brand or advertised capacity of a drive. For more on that distinction, see why a disk test is not a SMART diagnostic. If the drive repeatedly disconnects or reports errors, do not rely on it for the next owner's data. Replace it or have it inspected, and be clear about the problem in the sale listing.

What to include in a resale note

For a useful handoff, include the drive type if known, the connection used, the test date, and two or three readings from the same setup. Say whether the result came from the computer's internal drive or an external drive. Avoid claiming the drive is healthy based only on a speed score, since a speed test checks performance during that run, not every aspect of reliability.