OK I did some testing with ALFAT reliability:
One thread writes (mount, open, (write and flush continously until error detected)) a log entry every 1 second. The log entry contains entry number, date, and 500 '#' symbols. Another independent thread turns off power (via relay) for 5 ms ant random intervals from 500ms to 5000ms. 10000 power offs.
ALFAT tested was 1.0.8.
Test went trully good - card did not needed to be formated and data could be written and read after the test.
But check lines 6320 and 7770 (attached immages since log can not be added). Well in case of 6320 I suspect that it is normal if I disconnected power in middle of writing some unexpected/binary character blocks may appear. But with 7770 it is strange that just few odd bits change value. Can someone explain that effect to me?