[tanelpoder]

The issue in the enterprise (SAN) storage space is that there are so many layers where things can go wrong. Lost writes due to the OS kernel (like the fsyncgate), in-kernel storage interaction drivers, the storage array software itself, then disk firmware etc. Theoretically you could read back the just-written block and check if it’s what you wrote, but maybe it’s returned from some cache, before the bug happened.

Another scenario (OS, driver bugs) is that a correct block is written to a wrong location. Yes the write is persisted, but overwriting a wrong location. So now you have two incorrect blocks.