Hakuna is right, raid is better and you can avoid disk failures, that will happen. Guaranteed.
Keep in mind that a node is having massive I/O in matter of ms, all the time, is not like sporadically witting and reading.

Also take in consideration to use ECC RAM memories. ECC are crucial for a node.
If you want to be serious not amateur.

So a NUC not sure it could offer you these 2 features (RAID and ECC). You will need to find a custom PC. It could be small factor no problem, the size doesn't matter. Butt look for these 2 features to be offered.

Here read about RAID systems https://en.wikipedia.org/wiki/RAID
A RAID 1 is enough for your node. So with 2 identical disks will be OK.