When writing to disk and there's a loss of power during the write, what are the guarantees that the underlying block device provides? Is sector atomicity guaranteed or may corruption happen anywhere? Are blocks written consecutively in FIFO-fashion or may the controller reorder them before commening writes?
To answer this for a particular device, prngbb has been written. It essentially fills a portion of a block device with a reversible PRNG pattern with variable seed. It does this forever, in a bounded-buffer fashion. You run it, then wait until it has a few blocks written (it syncs after each iteration), then cut power.
Afterwards, you run the Python script to determine what happened.
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