On Wed, Jun 01, 2022 at 02:11:35PM -0700, Eric Wheeler wrote: > It looks like the NVMe works well except in 512b situations. Its > interesting that --force-unit-access doesn't increase the latency: Perhaps > the NVMe ignores sync flags since it knows it has a non-volatile cache. NVMe (and other interface) SSDs generally come in two flavors: - consumer ones have a volatile write cache and FUA/Flush has a lot of overhead - enterprise ones with the grossly nisnamed "power loss protection" feature have a non-volatile write cache and FUA/Flush has no overhead at all If this is an enterprise drive the behavior is expected. If on the other hand it is a cheap consumer driver chances are it just lies, which there have been a few instances of.
