That is a bug in CDH/HDFS, but it was an error and is now fixed. That's not diminishing the severity of the bug, but you can patch and get the correct behaviou

That is a bug in CDH/HDFS, but it was an error and is now fixed. That's not diminishing the severity of the bug, but you can patch and get the correct behaviour, without a performance hit. That is not comparable to what seems to be the case here with ES & MongoDB, where they deliberately (by design) accept the risk of data-loss to boost performance. Now most systems allow you to do make that trade-off, but an honest system chooses the safe-but-slow configuration by default, and has you knowingly opt-in to the risks of the faster configuration. I hope you consider editing your initial post - if you conflate bugs with deliberately unsafe design, we just end up with a race to the bottom of increasingly unsafe but fast behaviour.