Quickly spot-check any USB mass storage drive
for fraudulent deliberately missing storage.


The drive maps above are typical of the fraudulent drives which are flooding the market. This shows a drive sold as two terabytes (2TB) which actually only contains 62 gigabytes (62GB) of flash storage. Please see ValiDrive's complete report about this drive, below.

File stats for: ValiDrivefile download  freeware page
Last Updated:
Size: 94k
Oct 08, 2023 at 10:24
(139.30 days ago)
Downloads/day: 1,026
Total downloads: 142,266
Current Rank: 2
Historical Rank: 26

While putting the finishing touches on the major update to SpinRite (v6.1), one of SpinRite's pre-release testers encountered a drive that SpinRite flagged as unable to be used. It turned out this drive only contained storage at its front. After becoming aware of this significant problem in the industry, I purchased 12 inexpensive 1 & 2 terabyte thumb drives from Amazon... and every one of them was a bogus fraudulent drive:


In case you're curious, here are the Amazon links for the 12 drives above, which I purchased during September of 2023:

Why is this a serious problem?

At first this might seem like a minor annoyance: You purchase a 1 or 2 terabyte drive at a bargain price and you receive a 64GB drive instead. But that's NOT what happens here!

The drive appears to be the 1 or 2 terabyte drive you purchased. You plug it into your computer and everything looks fine. You can even copy files to the drive; as many as you want. And when you look at the drive's contents the files are there. But what's insidious is that the files' contents may have never been stored.

These fraudulent drives contain just enough storage – typically 64GB – to convincingly hold the file system's directory listing. But once its first 64GB of storage space has been filled, the contents of any additional files will not actually be stored. Their names, dates and sizes will be stored in the directory at the front of the drive. Everything will appear to be fine. But the files' contents will be blank because they were “stored” where no storage exists.

Operating systems do not verify that the data they write was actually written. They rely upon the honesty of storage devices to report errors. If a write error occurs, then the operating system will rewrite the data elsewhere. But these deliberately fraudulent drives never report any problems – they just silently discard any data written where there's no storage.

The first indication of a problem occurs when
you attempt to read back a stored file. Even that
will appear to work... but the file itself will be empty!
What does ValiDrive do?

ValiDrive performs a quick, random-sequence spot-check across the drive's entire declared storage space. At every location it verifies the successful storage and retrieval of random (unspoofable) test data.

A drive map that looks like this is what you hope to see:
A map like those shown at the top of this page are what you hope to never see.
But wait!   There's more...

(Of course there is!) While ValiDrive is poking around your USB drive, it notes the length of time required for each random read and write access. Once it's finished, it analyzes and summarizes the drive's access-time statistics in a final report:


You can get started with ValiDrive right away. The following pages contain additional information to answer any questions and help you get the most out of ValiDrive:

GRC's active web forums at are another great
place to explore and post your own questions, experiences and results.

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