@the_dude
hey man.. i found the same issue.. that raidz wants 4 or more vdevs. since this is an 'appliance' I think the sun engineers are making lots of assuptions to make this idiot proof for storage admins that dont want to learn or care about managing zfs at the command line..
if you try to put 2 pools on the appliance with the same configuration .. like 2 pools each a 2 disk stripe.. it will do it but complain that this is not best practice and you should just make the original pool larger.
to witt... I think they don't allow 3 drive raidz as its overhead is close enough to mirror that they prefer you use that.. and 4 disk 'fit' physically better in the appliance..
now.. to the fix.. I know.. tldr... you can drop into the command line by ssh into the appliance and type shell... you will get a full page warning on how this is the end of the world, you will void your warantee etc.. but just build your pool with the command line.. it will show up or be importably by the BUI/GUI and there you go..
the big issues for me using this right now is there does not seem to be a way to update.. or get security patches. you really cant tell what sun is using under the hood, uname -a tells you nothing about the underlying system and its been heavily modified according to orical hence the warnings about doing anything from the command line.
second is pool compatibility.. oracle is EOL and when this becomes unstable/unusable without further updates the only way to get the data off is with network copy to a openzfs based filer, that is provided it is still stable enough to stay up long enough for the zfs send ...
I also am trying to get my head around the wierd language they use for datasets --> projects.. etc.. an under the hood there is a very weird structure as to how they name and mount datasets... again.. to make it idiot proof it gets more complicated under the hood.
also, there seems like there is considerable resources being used for appliance storage... likely the survivable arc cache etc..
its very interesting and would love to play with it on my esxi all-in-one but since my existing pools are not compatible its not worth starting over with 20TB of storage on line to get into a closed, dead end OS...