SHR or RAID1 + question about scrubbing + backup

Hello guys,
New member here :slight_smile:

A couple of questions:

  1. HDD’s are cheap according to me. So I don’t mind sacrificing space.
    If all my data fits on the largest size HDD you can buy today, what is the most redundant setup?
    I would think 2 HDD in SHR or RAID1?
    RAID 5 or 6 is a bigger risk?

  2. SHR or RAID1 for a 2 HDD setup?
    I can’t seem to find a noticable difference.
    Are there pro’s and con’s?
    Safety of my data and simplicity are the most important.

  3. If you enable checksums and perform a btrfs scrub, can a 2 HDD setup (SHR or RAID1) perform self healing? Or is this not possible on a 2 HDD setup?
    I can’t find the answer.
    Some sources say yes, others say self healing is only for a multi disk setup with parity.

  4. Backup solution.
    I was thinking about a second NAS with 2 HDD.
    Only powered on for SMART + scrub tests or in need of a backup.
    That way I have 4 copies of my data: 2 in NAS a (online) and 2 in NAS b (offline + remote).

I hope the specialists here can help.