This project investigates the fake USB SSD drives that are available on EBay and elsewhere for bargain prices.
The drives are advertised in sizes between 500Gb and 8Tb, for prices from about $30 to $50. This price is quite ridiculous for a drive of this capacity, and is enough to ring alarm bells about the products. Sure enough, they are fakes and are useless.
It appears there are at least two variations - one is a small flatpack, about the size of a credit card but thicker. This exactly mimics the Samsung SSD form factor. The other is a long slim design with either a flat or a a fluted cover. In both cases they are packaged as a plastic insert into an aluminium extrusion, so they are quite hard to look inside - they must be cut open. There may be other variations on the market.
Update as of mid-2023:
These fakes are still around in large numbers. The presentation has changed, the claims have grown (64GB is commonly advertised and 512Gb is also appearing) and the prices have dropped. Some of the labeling uses known brand names - Lenovo is common. EBay and Ali seem to be doing little to remove them, Temu has a few. The old standby rule - if it's too good to be true then it probably is - continues to apply. If the reviews are genuine then a lot of customers are being taken in, but it looks very much like the vendors have found a way to submit masses of fake reviews. Genuine comments that the items are fake do appear.
On opening it up the deception is immediately obvious. The PCB consists of the USB connector at the end, a custom IC, a SD-card socket with SD card inserted, and a few miscellaneous components. The PCB is glued to the plastic insert, which is a tight press fit in the aluminium extrusion. Other variations have a larger PCB with two SD-Card slots (although only one is occupied).
The SD card is unbranded. It can be removed and formatted and appears to work well, although the size that is reported is a bit odd, such as 48Gb and 61Gb. It is possible that these are factory rejects that are usable but have excessive bad cells. Whatever, I would not trust them with important data.
The custom IC (a 24-pin SMD) has had any branding removed. In one case the original branding is almost visible under the scratching - it appears to include "MN...", "PY..." and "ATT...".
The task of the IC is to communicate with the SD card and the USB port, reporting the drive capacity to the host as advertised, and sending data back and forth from the USB port to the SD card. But of course this fails when the host tries to address any capacity above the size of the SD card. There are at least two different modes of failure - one simply trashes the card, making it unusable without reformatting. The other just reports the error and requires a file system repair. The particular error reported might actually be an error in the SD card.
The devices can be formatted and the formatter reports the advertised capacity, so the device somehow has the capability of fooling the formatter into thinking that the formatting has succeeded.
It is astonishing to think that a manufacturer would go to the trouble of designing and manufacturing a custom IC that can communicate with USB and manage a SD card file system in multiple formats simply so they could pull a scam like this. However, it is possible that the IC is actually a MCU with some clever programming, in which case the effort would be somewhat less, but still significant.
Presumably the rationale behind the production of these devices is that they can be sold at fairs and swap meets, and a quick test with a few Gb of data will satisfy the prospective customer that they work. By the time the customer realises they have been tricked the vendor has moved on. The rationale behind the on-line sales is a bit harder to fathom, as most purchasers would presumably test the capacity of the card for themselves and immediately demand a refund. Perhaps the on-line vendors hope that purchasers won't run into the capacity limitation for some time, so that they will simply write the experience off as a device failure rather than a fake device. The most unfortunate purchasers would be doing small backups for several months before running into the type of failure that trashes the whole card and makes the data unrecoverable.
If you are aware of the issue and prepared to take the risk of the seller not honoring their refund policy, then the devices are a good source of free SD cards, albeit unbranded and with an unknown usable capacity.