I think mine is Raid 0 - the version which gives you twice the drive space (6TB) and no redundancy. Just back it up is the advice - I do a full back-up every few months and partial as I add new music onto a secondary NAS elsewhere.
Melco were going to use Raid 1 (3TB) but found Raid 0 sounded far better by a large margin so they recommend that.
I use WAV for best SQ as there is plenty of storage space. I demoed Flac vs WAV and you should try it too to decide which you prefer (if any) and why. I found WAV sounded more natural with a darker presentation and better bass - Flac was a bit brighter - not massive but a worthwhile choice to go Wav.
…also I prefer the Twonky Server on the Melco compared to Minim Server - try both and decide is my advice, the do not sound the same.
DB.