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Verifying the SD Card

There has been a lot of discussion recently about bad SD cards which are not the advertised size. The card I was using with my Raspberry Pi always seemed a bit strange so I decided to check it and found the following command:

f3write

This command writes to every sector on the card and the corresponding command reads from every sector confirming that the write was good.

When I tested my 128GB card it was automatically eject after a few minutes and couldn’t be tested. I wondered whether the multi card reader that was plugged into the USB C port on my Mac was getting moved slightly due vibration and losing the connection so I tried again. The same problem occured.

Since I thougth it was a physical problem I decided to get a single function mini-SD card reader which arrived from Amazon the following day. Testing reading and writing to the card worked perfectly and that it wasn’t the card that was a fault but the multi card reader.

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