Fake Flash - Does your SD card have Alzheimer's?

[Bilgus]

Does your new SD card seem to just lose files after a certain limit?
Weird corruption issues?
Flaky reads and writes?
Did you buy it online?

You might have fake flash

What is Fake Flash?
Generally Fake Flash are factory seconds that have issues
Like lots of bad blocks or bad timings

Or even more common lately simply smaller flash chips
that have a fake capacity table to show to the user.

https://rmprepusb.com/tutorials/007-all-about-fake-sd-cards-and-usb-flash-drives/#There_are_two_types_of_%E2%80%98fake_USB_Flash_drives%E2%80%A6


Windows and android users can use some of the tools listed here:
https://rmprepusb.com/tutorials/007-all-about-fake-sd-cards-and-usb-flash-drives/

Similar tools exist for linux too or use 'dd'
F3 (Fight Flash Fraud/Fight Fake Flash)
https://oss.digirati.com.br/f3/
'sudo apt install f3'

NOTE:
These tools have destructive testing methods some have non destructive tests too
Be advised you should back up any data you care about.
Ideally run these tests before you put any files on the drive

FAKEFLASHTEST v1.1.5  [SSi]
[DRIVE]     249.0GiB Generic STORAGE DEVICE         
FFT - Quick Size Test (destructive)
:     (no label)   [DRIVE]     249.0GiB Generic STORAGE DEVICE         

Writing marker blocks to drive 3 at 800MiB intervals.

BAD MEMORY from sector 8185274 (3,996.0MiB) to sector 524281274 (255,996.0Mib)

WARNING: no memory detected at one or more locations.
Test took 1 seconds.
319 sectors checked.
                         *** FAILED ***

DEVICE HAS DUPLICATE OR BAD BLOCKS!

Recommended maximum usable partition size: 3,196.0Mib (approx. Last good Sector=8185274)

F3 probe 7.2
Copyright (C) 2010 Digirati Internet LTDA.
This is free software; see the source for copying conditions.

WARNING: Probing normally takes from a few seconds to 15 minutes, but
it can take longer. Please be patient.

Bad news: The device `/dev/sdb` is a counterfeit of type limbo

You can "fix" this device using the following command:
f3fix --last-sec=112570367 /dev/sdb

Device geometry:
    *Usable* size: 53.68 GB (112570368 blocks)
    Announced size: 1.91 TB (4096000000 blocks)
    Module: 2.00 TB (2^41 Bytes)
    Approximate cache size: 511.00 MB (1046528 blocks), need-reset=no
    Physical block size: 512.00 Byte (2^9 Bytes)

Probe time: 49'46"
Operation: total time / count = avg time
    Read: 49.75s / 2097717 = 23us
    Write: 48'53" / 8373838 = 350us
    Reset: 2us / 2 = 1us

F3 probe 8.0
Copyright (C) 2010 Digirati Internet LTDA.
This is free software; see the source for copying conditions.

WARNING: Probing normally takes from a few seconds to 15 minutes, but
         it can take longer. Please be patient.

Probe finished, recovering blocks... Done

Bad news: The device `/dev/sdb' is damaged

Device geometry:
                 *Usable* size: 0.00 Byte (0 blocks)
                Announced size: 953.68 GB (2000011264 blocks)
                        Module: 1.00 TB (2^40 Bytes)
        Approximate cache size: 0.00 Byte (0 blocks), need-reset=no
           Physical block size: 512.00 Byte (2^9 Bytes)

Probe time: 1'47"