Thank you for all you answers,
we are running the os on USB 3 which gives us really good results. The nuc only have 1 sata connector and there is no micro-sd connector neither.
Because I’ve to attend a summit, I wont be able to make some test before friday ( regarding what @Tom Elliot is asking) .
The ultimate aim is that my colleague can restage this micro-cluster whenever they want and check what are the real impact on on the OS layer when you’re working with new hadoop version ( e.g. we have face huge dependencies issue between centos 6.6 and centos 6.7 which was a pain in the ass to resolve it I don’t even one to mention centos 7).