Before deciding to choose unRAID, I tested windows 2016 pool. I liked how easy it was to setup everything, and the fact that its interface was similar to Windows 10 was a big plus. But, I discovered that in order to have something marginally comparable to a 2 parity setup, I needed to start with at least 7 drives! Also, I could not figure out MS setup, because it seemed to me I lose more space than 2 drives for dual parity, and the more drives I add to the pool, the more space is lost! It just did not make any sense to me.
Maybe it was meant for sophisticated enterprise level storage systems, but definitely not for me, unRAID was way ahead...Sorry, but when I saw that 5 drives reference I recalled my not so good experience with Windows 2016...