Anyone have any opinions regarding building a Mini-ITX box to serve as both a router and a NAS device?
What I'm pondering is building a little box and using the NVMe drive for the OS and OpenWrt, with an additional SATA SSD (or hardware-RAIDed HDD's, if supported by the mobo, or by using a RAID card) for the NAS.
The NAS would hold mainly backup files created by machines on the LAN, which would in turn be uploaded to Backblaze using rclone and cron.
I'm mainly concerned about security. I can't think of a good reason why an internal SATA drive or RAID array would be any more vulnerable than a drive connected via USB, but maybe someone smarter than I am can.
If You plan use MiniPC think about virtualization. Proxmox is very nice hypervisor - you could use LXC containers and fully virtualized OSes. Just run one VM with Openwrt ans second with FreeNAS or whatever. Even with one disk Proxmox with ZFS provide acceptable data security. Of course if You could use 2 disks even without hardware RAID, ZFS is Your best friend and take care about data.
The i5 is plenty enough IMO. I have a little homelab with an i3-9100 on a Jonsbo C2 case and been using it for about a year now without any major heating issue. I have a couple of VMs on it but only uses about 3 of them in 24/7 (pfsense, OpenWrt x86 and Windows), all in Proxmox.
I've started testing Proxmox on Pentium Silver J5005 with 8GB RAM, mSATA SSD and SATA HDD MiniPC (2 VMs, 1 LXC container) and hardware is usually boring
Now it's enough for my needs but in future final platform will be Ryzen Embedded (as it matures and becomes more accessible).
I was running OpenWRT as a "NAS" with a WD GOLD 12 TB using rsync for backup to USB HDDs and an APU2 as hardware, it was a simple solution and I did the user/permission config CLI which was good cause i learned a lot
It worked excellent for a long time until I upgraded to OpenWRT 19.0.3 and LUKS stopped working for me on my hardrives
MiniPC (2 VMs, 1 LXC container) and hardware is usually boring 
