Can't use "usemaximimsize" on a thin provisioned virtual drive. If you changed that to fixed it would have worked or as you found out just set a size, ie 60tb or whatever number you wanted. In server 2012r2 if you did do a mirror space over 4 drives via the guidelines it would have made a two column mirror space. The gui will only limit you once you get past 8 column. So if you were doing a 20 drive mirror you would want to use powershell to specify # of columns as 10 or else the guidelines will limit you to 8.
On a side note a bit of obscure info on column count dual parity maxes out column count at 17 otherwise I am 90% positive all mirror and simple spaces have unlimited column counts. I have set up 32 and 48 column simple spaces to test absolute performance a few times.
I guess it makes sense that you can't do both thin provisioning and usemaxsize. I would just really really have liked powershell to just tell me that instead of giving me an error that is compeletly non descriptive. I wasn't sure about how the default configs would work in 2012r2, so that is why I wanted to do the powershell method, since then I would be 100% sure of what would happen. (And I didn't see a columns option in the multiple times I've used the GUI, maybe I'm just blind).
Thanks for the info though, I'm learning a lot about Storage Spaces, it still is somewhat unclear to me though.
