MooseFS and hard drives?

Question

System administration

Good afternoon.
After some unfortunate events, I had to replace the admin. At first glance, everything is simple. There is a cluster assembled on 3 computers with debian and MooseFS on board, but stumbled over the problem that 1 device is the master, 2 other chunks, but 2 disks per chunk and are entered into the system as separate hard ones, that is, the master sees them as 4 separate discs! Of course, I didn’t touch anything, as they say - “you don’t need to repair what works”, but I still have a strange residue and only now it dawned on me that the disks are not in raid1, but each separately, which means that one of them is installed system. Now the question is, what happens if the disk with the system breaks? I understand that the system will not boot and re-install everything, BUT the data on another disk will also die, or will the master determine them after installation and mounting normally? It is not yet possible to scatter disks on different machines, what to do and what is the best thing to do?
Thank you all in advance