Well, everything is ready to assemble. I ordered 3 extra new drives of 4TB, I managed to squeeze the existing information on 1 of those drives, although I had to delete one of my Truecrypt backup files (which was 1TB), but I still have 3 of those left, so no real big deal. But now I am thinking about Raid 5 in general. If I look for "Recover Broken Raid 5 Array" then the information I get is pretty little. It does not seem that in Windows 10 there is a native recovery option for raid 5, even though you can make a "storage pool' in Windows 10 (Or I completely missed that option). The homeserver contains basically mostly movies and tv-shows and a Truecrypt container for my private photo's and video's. But that Truecrypt container I also have on my own pc, and two of them on another pc. I regularly synchronize them with "FreeFileSync", works like a charm.
So with the risk of any of the 4 drives can crash I am also thinking about two sets of a raid 0 array. The benefit of that are two things: Speed and keeping all space. Cons are of course, no redundancy at all, and if one drive goes, you loose the data on the other as well, without option of recovery. But it would only apply to one raid 0 array at that point. With raid 5 ALL hard drives are involved and if you do not recover proper then you loose ALL your information. And another con is that you also loose 4TB of space. Question you probably would ask: How important is the data? Well, I did burned over 100 Blu Ray disks with tv-shows, until my Blu Ray burner gave out (and I never bought another one again), and most movies are redownloadable, and the backupfile is present on my own computer and on another computer twice. And normally I also keep a hard drive off site, but currently I don't have that. Raid 5 or double Raid 0? I am not sure anymore.