I&#x27;ve explained all this so there&#x27;s nothing new here at all. I&#x27;ll try again if it helps.<p><i>&gt;Don&#x27;t believe me? Take those four disks (you need four at minimum) in your RAID6. Your array can survive two disk failures. Now I build a RAID1 with four disks. Mine can survive three disk failures.</i><p>Apples and oranges again...<p><i>&gt; Yes, there&#x27;s a capacity hit, but it&#x27;s been repeatedly established that it&#x27;s not capacity that matters.</i><p>This is not established. This is something you keep saying but makes no sense. My NAS has 4 2TB disks, I&#x27;ve configured it as RAID6 for 4TB of space where any two disks can fail. RAID10 is strictly inferior to that and RAID1 would only give me 2TB of space which is not enough for me. This result is generalizable. For a given number of disks and a given target array usable size the n-parity RAID configuration always has superior redundancy to the RAID10 configuration, there&#x27;s no way around that.<p><i>&gt;Your points are much more valid when they&#x27;re targeted at RAID10 instead of the concept of mirroring in general.</i><p>My points have always been about RAID10 and not RAID1. If RAID1 is enough that&#x27;s always the better option as obviously it&#x27;s not possible to improve on &quot;you have N disks and N-1 of them can fail&quot;.<p>Note that&#x27;s also the reason RAID5 implementations are limited to 3 disks minimum and RAID6 to 4 disks minimum. In theory you could configure a RAID5 with 2 (1+1parity) and a RAID6 with 3 (1+2parity) but since it doesn&#x27;t make sense to calculate parity of a single disk that just ends up meaning RAID1.