In a random, non-repeating sequence, at each of 576 separate evenly spread locations on any drive, ValiDrive reads the current contents of that region. It then fills that region with random “data noise” then reads back the region's contents to verify that the “data noise” was actually stored. ValiDrive then always rewrites the region's original data to restore whatever data may have been originally stored there.
For in-depth analysis, Gibson's "SpinRite" can be used -
The two programs are complimentary but very different. ValiDrive quickly checks for the presence of any storage at 576 locations across a drive's storage media. SpinRite thoroughly, deeply and fully examines, verifies, and exercises any drive's storage media, while also performing comprehensive data recovery if necessary.
So, ValiDrive is a “quickie” test to see whether any storage is present, whereas SpinRite is the heavy hitter that verifies every byte of a drive's storage to verify its integrity and reliability.
SpinRite is a data professional's tool at a hobbyist price - inexpensive, but not free.
https://www.grc.com/sr/spinrite.htm
Validrive is less than 100K bytes! You could download and test it in 10 minutes. That should answer any questions you may have.
Spinrite had utility for combating data loss inherent to the HDD medium... I don't like the idea of ValidDrive because it's a paid user tool to fight fraud, that's a bad incentive, you don't want to benefit from that, it should be free and open.
Does this test actually spot modern fakes? My understanding was that they typically used simple modulo addressing such that any write was immediately readable, and even large continuous chunks operated perfectly fine, it just also "overwrote" that address every 4GB or whatever.
Windows is….. significantly more challenging.