FakeFlashTest.exe - Diagnosed a fake 16GB USB Flash drive in 27 seconds!
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SD Insight SmartPhone app for SD cards
You can download the free Android app SD Insight from the Google Play App Marketplace which will reveal the manufacturers pre-programmed details of your SD card. This does not actually test the card, but it can give a good indication of whether the card is genuine or not.
There is also a Google Play free app. called 'SD Card Tester' that will write a large file to your SD card (slowly!) and read it back here (note: double-tap to change folder).
What is a 'Fake Capacity' USB Flash Drive or SD card?
Many USB flash drives and SD cards are being sold on eBay and other auction sites at very cheap prices (too cheap!). These USB pens are usually of a high capacity (16, 32GB, 64GB or 128GB) and usually from the Far East, but some UK sellers also sell these too. 98% of these sellers are selling 'fake' USB Flash drives (fake UFDs) - either knowingly, unknowingly or I-don't-really-want-to-know-ingly!
WARNING to all eBay buyers - Always check the seller's feedback - if anyone has given neutral or negative feedback because of 'corrupted' data, then it is likely that the product is counterfeit/fake. Always test the memory using RMPrepUSB - Quick Size Test or FakeFlashTest before you use it. It would be a shame if you used a 64GB SD card for all your photos on that 'once-in-a-lifetime' holiday to Africa, only to find out that all your photos have gone! Also, please ensure you give the seller negative feedback and report them to eBay for selling fake goods - if they knowingly continue to sell fake goods they are criminals and don't deserve good feedback! Also, get the eBay seller onto the eBay Fake Sellers list here.
Buying an SD card on eBay - If you are buying an SD/SDHC card from an eBay seller, check the full description very carefully. Some sellers are advertising a '16GB SD Class 10 SDHC card' and then in the description say 'these cards have been tested and may vary from 2GB to 32GB' and 'this is normal for cheap cards' and even 'the data you store will be compressed so don't worry if you can only store 2GB as really you can store more'. This is all a load of rubbish! These cards are 'fake capacity' cards and have been deliberately manufactured to deceive the buyer! eBay seem quite content to allow these sellers to sell their fake goods!
If you buy one of these fake UFDs or SD cards, they will appear to work fine and Windows will show them at their 'rated' capacity - for instance a 64GB UFD will appear in Windows to have a capacity of say 61.3GB, you may even give the seller positive feedback on eBay because they appear to work fine. However, these UFDs actually only contain about 2GB of real memory. When you start putting your files onto it, everything may appear to be fine - until you fill it up with more than 2GB and then it completely corrupts all the files on it! Bet you wish you hadn't paid £20 for it now!
The fake product is usually made from a poor quality or defective smaller flash memory chip (and probably a 2nd rate 'reject' memory chip obtained from the trash can at the back of the factory!), but the controller has been programmed to falsely report it's capacity as say 64GB to Windows.
Don't be caught by these cheats. Simply ask them to test the UFD using RMPrepUSB, FakeFlashTest or H2TESTW before you buy it. If they refuse then walk away from the deal! Explain to them that if the UFD passes H2TESTW they will get a lot more bids if they state this in their adverts.
Do you have a fake Kingston Flash Drive? One simple way to check, is that usually Kingston print text onto the metal USB connector which has the model number and capacity + other numbers. If your Kingston drive has no printing on the connector, it may well be a fake!
How to test a suspect UFD or SD card
If you have a USB Flash drive, try using ChipGenious. Often this will reveal the true size of the memory chips(s) fitted by the manufacturer. The screenshot below shows a fake 16GB USB Flash drive containing a JS29F16G08AAMC1 memory chip which is a 16Gb (Gigabit) or 2GB (GigaByte) memory chip. It therefore cannot possibly hold 16GB of data!
NEW! FakeFlashTest.exe - test your suspect 'fake' SD card or USB Flash drive in just a few minutes (rather than hours!) - read my blog.
Tip: For testing SD cards, you can buy a USB 3.0 card reader for £5 from Amazon - these really improve data transfer times (even if just using them on a USB 2.0 port). Cheap USB 2.0 card readers are notoriously slow!
A good practical test of a USB flash drive or SD card is to fill the drive up with .jpg photos (at least 5GB worth). Then try looking at ALL the photos to see if they are all accessible and not corrupt. The thumbnail view in Windows Explorer will do this for you quite nicely!
If you have bought a 'bargain' UFD, you can test it using the 'Gold Standard' test H2TESTWwritten by Harald Bogeholz for c't magazine. This test is very thorough but very slow because it tests all bytes of unused memory (even if it doesn't exist). The test utility is not included in the RMPrepUSB download but there is a link to the download on the RMPrepUSB help form - Just run H2TESTW.exe and select English as the language and the empty USB drive that you want to test. H2TESTW will fill up the empty, unused space on the UFD with large files but will not destroy any files that you already have on the UFD (but it you may lose all the files if the UFD is a fake one due to corruption!). The test can take 4-8 hours to test a good 16GB drive and considerably longer if it is faulty.
A much quicker test is to use the RMPrepUSB Quick Size Test button --->
This test does destroy all data on the UFD and you will need to re-format the drive as FAT32 using RMPrepUSB after testing it. But a 16GB UFD can be tested in just 6-10 minutes.
Note that this is not a thorough test of all bits in the memory but it will certainly detect a 'fake capacity' memory product - if it fails RMPrepUSB or FakeFlashTest, then it will also fail H2TESTW, so you might as well use RMPrepUSB to test it first as it will be much, much quicker!
Bought on eBay - 32GB SD Class 10 card that is actually only 4GB and wasn't even Class 4! (click to enlarge)
If RMPrepUSB Quick Size Test passes, then (if you have the time) you should reformat it and then test it twice with H2TESTW just to make sure the memory is all good quality (if you have the time!).
If it fails, RMPrepUSB will tell you the approximate true size of memory present in the pen (though the memory may be faulty/unreliable). You could set the SIZE box in RMPrepUSB with the reduced size and then reformat it as FAT32 to use what little memory there really is present - but don't use it for anything important as quite often that memory is faulty or will develop a fault at a later date!
See the bottom of this article for a typical result when testing a 'fake' flash memory drive.
If you have a fake UFD, you cannot easily 'repair' them and even if you reformat them to their true (reduced) capacity using RMPrepUSB, the memory is probably of such poor quality (reject chips sold off by the factory as faulty) that it will sooner or later cause corruption of your most important files. You may not even realise your files are corrupt for months and may have lost the original files by the time you find out!
To reprogram a fake flash memory drive, you will need to find the manufacturer's tool to re-program it with the true capacity - for an example on how to do this see Tutorial #39.
For more details about fake UFDs, see SOSFakeFlash website here.
ATTENTION:If you have a USB Flash Drive that does not seem to work with Windows and causes the computer to slow up or stop responding whenever you try to use it or access it - please read the tutorial #23 here for instructions on how to fix it.
If your USB Flash drive does not seem to format using RMPrepUSB, check that Windows has assigned it a drive letter. If not use Drive Manager to add a drive letter to the drive. The easiest way to access the disk management console is go to Start-Run and enter "diskmgmt.msc" right-click on the USB drive area and choose 'Change drive letter and paths...' - then add a drive letter.
Here is a typical 'fake' flash drive bought from China off eBay. It was sold to me as a 16GB Flash drive and has 16GB printed on it.
However, it is actually a 2GB Flash chip mapped 8 times into a 16GB address space - writes past 2GB don't actually store the data but just report back 'OK' - hence writes and reads from 16GB to 2GB are very quick!