Testing for Counterfit Flash Drives

[Bob_Schor]

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@emw129 wrote:

That is why I no longer sell Thumb drives from anyone.  Until I can find a way of proving that a 128GB Thumb drive is actually 128GB.

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So if your goal is to resell 128GB Flash Drives that you get from a source you don't trust, you could (it seems to me) easily test the drives capacity by writing 128GB worth of data whose contents you know (for example, U64 digits from 1 to16,000,000,000, perhaps hashed to give you a higher level of confidence, then reading back and comparing the results.  If there are <128GB on the drive, you won't get back 16GB of unique 8B (=U64) data that you wrote.

Didn't this simple idea occur to you?

Bob Schor

[rolfk]

Except that those type of drives not only will be smaller than advertised but likely also drop dead slow, and writing 16GB of data onto them is likely going to be a very time intensive exercise that eats the few cents of earnings that you can make on such trash hardware.

Basically if such a drive doesn't provide the highest possible USB3 transfer rates it's high capacity is anyhow wasted and very likely not true anyhow.

[Bob_Schor]

Sigh.  You are right, of course Rolf, but in the 10 months since the Poster "originally" posted and "most recently" posted, he could have easily run a test (my back-of-the-envelope calculation suggests that writing 128GB of data at USB 2 speeds, call it 32MB/sec = 4000 seconds takes between 1 and 2 hours, not a burden over a 10-month span).  Nobody seems to want to be an "experimentalist" (or a "scientist") anymore ...

BS

[rolfk]

Right, a prefect scientific experiment. But it seems this guy wants to earn some money by buying them cheap on Alibaba or elsewhere and reselling them here without a bunch of angry customers coming after him to burn down his home 

It is recommendable that he at least worries about these things, although the motives may be still mostly self serving. There are enough who have less scrupules about such things.

But if you want to sell these, a two hour test for every of them is a serious burden that eats up any possible profit from such a transaction very quickly.

[altenbach]

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@rolfk wrote:

Except that those type of drives not only will be smaller than advertised but likely also drop dead slow, and writing 16GB of data onto them is likely going to be a very time intensive exercise that eats the few cents of earnings that you can make on such trash hardware.

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Of course you could turn the argument around and just do a quick speed test using a relatively small file. If the read/write speeds are significantly slower than what they are supposed to be, the thing is probably fake. 😄

(See Bob, I am an "experimentalist" too :))

[Bob_Schor]

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altenbach wrote: (See Bob, I am an "experimentalist" too :))

C'mon, Christian, I knew that!  Who else would be interested in non-linear fits?  [I still need to write up my Simplex routine for your blog ...].

BS

[emw129]

Most of these fake Thumb Drives / Flash Memory products aren't just sold on Alibaba, but are also sold on Amazon, eBay, Bonanza, Shopify, etc., ...  all over the WEB.  I'm just looking for a quick easy way like writing to specific spots on the Thumb drive at hardware levels like at every 1GB page sections before and after each 1GB pages, so that only about 128 cycles are required to confirm a 128GB or (2,000 x) for a 2TB thumb drive has the true memory it says it does.  A lot of these fake Thumb drives dongle the thumb drive OS to into reporting more memory than actually exists.

[emw129]

It is also about money per time.  if you got paid $480 but spent 480 hours making $480, then you only made $1 per hour, way below minimum wage.  But if you could make $480 per hour, you are now making $1 million per year.  If you only worked 40 hours a week and 52 weeks a year.

Now how do de-fragmentation software programs do their job?, They must have direct access to each point in memory or page in memory to  defragment memory on the drive or solid state drive.

[rolfk]

Defragmenting an SSD, which flash drives are too, is not only useless but in fact a sure way to shorten its life expectancy significantly! There are no mechanical moving parts in a flash drive, so defragmenting doesn't really give any speed advantage like with a mechanical hard disk, which has to turn an entire turn to access a different sector on the harddisk if it isn't subsequent. And they rotated with 5400 to 7000 RPMs but that still means huge amounts of time for one RPM.

But flash cells have a limited number of write cycles they can survive and defragmenting is generally a very intensive moving around of data sectors to recombine files.

Every decent defragmentation program nowadays will simply refuse to work on a flash drive or SSD.

The flash drive still presents a software interface to the OS that looks like a rotating harddisk for the sake of backwards compatibility so a stupid defragmentation program might attempt to defragment the "harddisk" but in doing so will basically shorten the life for the flash drive. 

[Blokk]

I really do not understand what is the goal here. You want to test thumbdrives from unreliable sources/sellers to see whether the reported storage capacity is fake or not. What about the expected life time of such cheap products? I can imagine, such low quality products might have the stated storage, but much lower maximum write/read cycles. Or higher chance to get malfunction...There is no way you can test these products for these parameters. So you end up reselling low quality products anyway...Yep, you could make money from this I guess. But the other side of the story...well...

If you buy a flash drive from a reliable source, they give proper traceability, they have customer support, they give you few years of guarantee in some cases...