SD card fake/corrupt? check with f3 on slackware


b_o_b

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Sep 7, 2010
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I have been playing around with Slackware see here and tried to install it on a Toshiba M203/EA 64 GB SD card.
Installing Slackware didn't work on these cards only once after formatting to EXT-2 but followed by error messages and endless fsck loop. So I wanted to be sure the 5 cards I bought were legit and not fake.

Installed f3 on slackware with https://slackbuilds.org/repository/14.2/system/f3/

f3 is a great tool to check if a card is fake.
https://fight-flash-fraud.readthedocs.io/en/latest/usage.html

Followed the suggested method and did a f3write with slackware on the best performing card, followed by a f3read. f3writes severel 1Gb files until the SD card is full and f3read reads the file for issues.
f3read found one corrupt file but file (32.h2w) there were several files with deviating info (e.g. 17.h2w / 21h2.w). See log file for the full check.

Validating file 17.h2w ... 10762097152/ 0/ 0/ 0
Validating file 18.h2w ... 2097152/ 0/ 0/ 0
Validating file 19.h2w ... 2097152/ 0/ 0/ 0
Validating file 20.h2w ... 2097152/ 0/ 0/ 0
Validating file 21.h2w ... 14522097152/ 0/ 0/ 0
Validating file 22.h2w ... 2097152/ 0/ 0/ 0
Validating file 23.h2w ... 2097152/ 0/ 0/ 0
Validating file 24.h2w ... 2097152/ 0/ 0/ 0
Validating file 25.h2w ... 2097152/ 0/ 0/ 0
Validating file 26.h2w ... 2097152/ 0/ 0/ 0
Validating file 27.h2w ... 2097152/ 0/ 0/ 0
Validating file 28.h2w ... 2097152/ 0/ 0/ 0
Validating file 29.h2w ... 2097152/ 0/ 0/ 0
Validating file 30.h2w ... 2097152/ 0/ 0/ 0
Validating file 31.h2w ... 2097152/ 0/ 0/ 0
Validating file 32.h2w ... 126162/2097152/ 0/ 0/ 0
Validating file 33.h2w ... 2097152/ 0/ 0/ 0
Validating file 34.h2w ... 2097152/ 0/ 0/ 0

Used the SD card formatter to format all the SD cards and still are all similarly 'unreliable' (on multiple devices - even windows had problems with recognizing one of the cards). Based on the test my conclusion is that I've probably haven't received counterfeited cards but a bad batch. The cards were pretty cheap, maybe the Amazon shop was aware of issues (I've sent the info today).

Anything else I can do/check?
 

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elw3

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If 5 of my cards would report failure i would rather question if the card reader is OK.
Other than that is unlikely that toshiba sells a bad batch within their branded packages.
 

b_o_b

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If 5 of my cards would report failure i would rather question if the card reader is OK.
Other than that is unlikely that toshiba sells a bad batch within their branded packages.

The SD card I checked is formatted and fully checked with f3 in my Pandora. I've also used several card readers and two of them are Anker.
Haven' t tried the same approach with another Pandora and another card to see if the issue is consistent.
 

b_o_b

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Tried something else. Formatted one sd card to exFAT and ran f3write and f3read again. No corrupt sectors during reading this time.
I didn't understand why in the write phase there were sometimes numbers before writing the file
e.g.
Creating file 32.h2w ... OK!
Creating file 33.h2w ... 55.6OK!

I thought the 55.6 might indicate an issue, but I think that is just a percentage of the process. Still one thing that I don't understand during validating and that are files that have an additional number before 2097152.

Validating file 20.h2w ... 2097152/ 0/ 0/ 0
Validating file 21.h2w ... 14522097152/ 0/ 0/ 0
Validating file 22.h2w ... 2097152/ 0/ 0/ 0

The summary doesn't show any corrupt files or other errors though. Maybe that is also not an error and then the card could be fine. Will fill it up with some Pandora stuff and lets see how it works in practice.
 

HelenF

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Jun 22, 2013
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That output is odd. But if the summary says 0 for "data lost", maybe it's fine?

If anyone is wondering, F3 works fine on SuperZaxxon too. At one point I built a recent version in CodeBlocks, and got standalone binaries which were tiny enough to put on the NAND without concern. Think I might have posted them on the forums, but not sure about that.
 
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