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You mean a simple reformat with fat? Or what’s in your opinion the best test when getting a new SD card?
You mean a simple reformat with fat? Or what’s in your opinion the best test when getting a new SD card?
Read back data and compare against the same pseudorandom data with a same fixed seed.
Or just make a random data file the size of SD card and write/read back compare, if you don't care about having to store the big file and also testing for potential local disk corruption at the same time.
It's also possible to write 64bit address of each 8 byte block to every such block, and avoid pseudorandom generator, and potentially have more insight to what happened when the block ends up mapped to unexpected location.
Cheap, fake cards will often fail this simple basic test.
There are a number of readily available utilities to further test performance and reliability.