On of the more insidious types of errors are phantom writes, which are thankfully rarely seen in current storage hardware. This can cause data loss where everything otherwise looks correct -- I/O, integrity, and structure -- because what you read back may be a valid but old version of what was written to storage.

This type of error can be detected with sufficiently robust integrity checking e.g. some type of durable Merkle tree, but ensuring that integrity checking can reliably detect phantom writes has a relatively high performance cost so many storage systems just assume it will not happen, given the low prevalence and high cost. FWIW, I think this is the correct tradeoff for many storage systems, where it is not a highly probable source of data loss in practice and some types of replications architectures make it relatively straightforward to detect after it has occurred even if not immediately.