Write pseudorandom data to the whole card with a fixed seed.
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.
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.