Help Files - Memory cards - h2testw


Well-Known Member
Jan 27, 2013
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Sydney, Australia ~ Shenzhen, China
Dash Cam
Too many ¯\_(ツ)_/¯
H2testw was developed to test USB sticks for various kinds of errors, you may have been recommended to test your memory card using h2testw, one of the reasons we use this software is it is useful for checking memory cards for their true size, fake cards most often have a fake partition table to appear larger than their true size, h2testw is good at identifying this problem, fake media is a problem particularly with online sellers, the software will identify if you have fake memory but even if it passes the test and the size is true does not also mean that the card is a good choice for dashcam use, check with the manufacturer of your camera as to which cards they recommended and also any they advise against

h2testw can be downloaded from here

The program is a simple executable file that will write a series of 1gb files to your memory card, it will reserve 1MB of space from the card to run and will test the rest of the available space, the card should be formatted prior to running the test, the software is German but has English option also

On startup select English and then Select Target to browse to your memory card drive

01 h2testw startup.jpg

Select your drive then select OK

02 h2testw select drive.jpg

Select Write + Verify

03 h2testw target selected.jpg

The program will show the following warning, select OK

04 h2testw warning.jpg

The following will show the progress as it is processing

Note: it's a slow process, a healthy card will take around 1 hour per 32GB of memory

05 h2testw progress.jpg

When the process is finished it will show the test results (this is a healthy card)

06 h2testw test finish.jpg

The card will be full of test files, these should be deleted once the test is complete

07 h2testw test files.jpg

If your test looks like the results above your card is the stated capacity

A fake card will give different results, you may see something like this where it can't even write to the card

08 h2testw fake card results.jpg

Alternatively you may see a result that shows some of the space is ok but not all, for example these are the results of fake card, the card was sold as a 128GB card but only has 32GB of memory and a fake allocation table to tell the host device that it was 128GB, initial tests of this card in Windows would show it as being 128GB however once the real memory limit was reached the recordings would fail

Warning: Only 255898 of 255995 MByte tested.
The media is likely to be defective.
28.9 GByte OK (60783335 sectors)
50.1 GByte DATA LOST (105131938 sectors)

Details:0 KByte overwritten (0 sectors)
0 KByte slightly changed (< 8 bit/sector, 0 sectors)
50.1 GByte corrupted (105131938 sectors)
0 KByte aliased memory (0 sectors)
First error at offset: 0x000000073ef5ce00
Expected: 0x000000073ef5ce00
Found: 0x61f88239add67602
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