Tuesday, November 17, 2015

The 512GB USB Key

Subtitle: How do they do that?

When somebody offers you a 512GB (0.5 TB !!) portable USB key for less than 10USD  (6 GBP) well it was irresistible, not because I though it would be a bargain, but  because it would surely be a fake.

And no shit Sherlock, it does in fact turn out to be


The interest was to find out what exactly is going on here.  And that's what this article is about

Basic USB Key Facts

- The stated capacity of the key was 512GB

- I checked with the ebay seller before purchase they really meant 512GB and not say 512MB.

After a few weeks of waiting for it to arrive to Switzerland from China it came and I did some basic enquiring

So the key does in fact report itself to be a 512GB key!

Physically the key looks like a Kingston Data Traveller. The trouble is that Kingston never made a 512GB Data Traveller, so right from the start, I was deeply suspicious!

Typical Cheating Tactics

The typical cheat is to map the physical disk to a much larger disk and truncate any writes past the physical disk to a modulus of the key.  Example:  I mean that say it's actually an 8GB key.  They writes to 8GB + 1 byte get mapped to the first byte of the 8GB range.  Similarly writes to 16GB + 1 byte, map to the same place.

In this scheme writes will succeed so long as the FAT remains intact.

The Testing Machine

In order to isolate the effects of dodgy testing software or something nasty on this rather suspect USB key I wanted to test on an isolated machine.

By the way this superb computer is for sale in Switzerland at a totally knocked down price.  See here.  Otherwise Marcus and Agata may go hungry this Christmas :-(

Programs Used to Check

(Click on the program heading link to goto an information page)

MiniTool Partition Wizard

A small and compact partition utility able to create, resize and format partitions.   This was the main tool for reformatting the USB key or changing the single partition after various utilies destroyed it.

There are other paid versions of the tool but for me too expensive to buy.


Allows for a FAT format with larger allocation sizes.

Sure, you can use the command line format /?  to do this but a graphical tool is somehow quicker.

Hard Disk Low Level Formatter

Good for wiping MBR and removing partitions quickly.   (The MiniTool can do all of this for you also)


Identified the drive and all performance tests worked fine. Okay it's really slow being based only on USB2 interface, but for 6GBP, come one!


Simply an awesome  (and I don't often use that word!) program to help you create a Bootable USB key.

Now, no matter how I formatted or partitioned this key was not recognised by Rufus.  An immediate Red Flag to me.

ChipGenius v4_00_0807

I downloaded this tool from a fairly dodgy website but it detects low level information about the USB Key.

More information about the key but not its size.

Flash Drive Tester

This is a 2009 and thus quite old tool from www.vconconsle.com  a company that specialises in hardware duplicators.

This did initially not spot any errors when I used the drive as is with one enormous FAT32, 512GB partition.  The first write part took 10 hours!

Then it went to the reading and comparing part and did find errors


This utility either hung, repeatedly when performing the Quick Size Test, or if used to Test Free space

Then it never found a problem :-(


Warning: Only 8170 of 8171 MByte tested.

The media is likely to be defective.
7.1 GByte OK (14978687 sectors)
856.1 MByte DATA LOST (1753473 sectors)
Details:0 KByte overwritten (0 sectors)
0 KByte slightly changed (< 8 bit/sector, 0 sectors)
856.1 MByte corrupted (1753473 sectors)
0 KByte aliased memory (0 sectors)
First error at offset: 0x00000001c91cd000
Expected: 0x00000001c91cd000
Found: 0xe1f2dfa8398e5ea0
H2testw version 1.3
Writing speed: 6.34 MByte/s
Reading speed: 14.6 MByte/s

H2testw v1.4

So this found an issue.


Able to correctly look at USB characteristics , but does not show any sizing information


Tool did not work. Hmm.

Test Results

Error at offset 0x 0000 0001 c91c d000

(decimal 7669075968, 7313 MB)

h2testw seems to be the killer fault finding utility.  It found an error pretty quickly and determined that really we are dealing with a roughly 7GB physical key here.

FakeFlashTest hung or did not find any problem

None of the info tools were able to show the correct or perceived size.

Some Hilarity

The USB key was bought from eBay seller chenrunru2014

At one point in the 'you sold me a faulty USB' exchange I received the classic text:

dear customer 

we are sorry to hear that 
as the item has a large capacity 
would you please wait one or two minutes for it if there is no connection at first 
or try it on another computer
and please don't load too many files on it at one time
please let us know if it works now

Kingston do actually sell a 512GB and even 1TB USB drive. It is called the  DataTraveler HyperX Predator.   The 512GB version is available for about 400 CHF , which is about 270 GBP and not 6 GBP, the amount I paid for the Fake Key!