Hi all. I am getting ready to build my first NAS, I plan on using my old gaming PC for it, it has multiple hard drive bays, i5 processor, 16gb ddr3 ram and a GTX 970 video card.

Currently I have a 14tb external harddrive that's almost full, and I just bought 2 used WD Ultrastar DC HC530 14tb hardrives. My plan is to setup both hard drives as a raid 1, and transfer all my data from my external harddrive over to my hdd's and use a 250gb SSD for TrueNAS. Then probably re use my external hardrive for more linux isos since I'm impatient, until I can grab another 2 HDD's

I'm mostly anxious about somehow losing all my data when I make this transition since I have zero experience when it comes to running a NAS, is there anything I need to be on the lookout for, or do when I do this? Anything is appreciated! Many thanks