@loic.lopez This would be possible but highly inadvisable and technically difficult to maintain (unless only one was attached at a time that is). And you are almost certain to have major headaches and conflicts and potentially data loss as a result of mixing these systems. And you would be constrained to using only bios boot switching and system updates on either side could change / break / confused the other side.
I would strongly advise against this and don’t think you are likely to get much help on the forum going forward with such a compromised solution. So that might be a thing.
Hope that helps.
But it may be informative to know that Rockstor can work on pretty low end hardware. See the Minimum system requirements section in our docs. Plus it’s a lot more fun to experiment with a system that can’t inadvertently wipe out one of your other systems.
Let us know how you get on with your build.