With mirror vdevs if you lose the wrong 2 drives you lose everything. I can lose any 2 drives and be totally fine.
The probability of losing the wrong 2 drives at once is small, sure. But I would rather just not care about that probability. And I don't lose half my capacity, which for a home user (I don't have an unlimited budget!) matters a whole lot more than having the absolute best iops.
> But wait, why would I want to trade guaranteed two disk failure in RAIDZ2 with only 85.7% survival of two disk failure in a pool of mirrors? Because of the drastically shorter time to resilver, and drastically lower load placed on the pool while doing so. The only disk more heavily loaded than usual during a mirror vdev resilvering is the other disk in the vdev – which might sound bad, but remember that it’s no more heavily loaded than it would’ve been as a RAIDZ member. Each block resilvered on a RAIDZ vdev requires a block to be read from each surviving RAIDZ member; each block written to a resilvering mirror only requires one block to be read from a surviving vdev member. For a six-disk RAIDZ1 vs a six disk pool of mirrors, that’s five times the extra I/O demands required of the surviving disks.
I think it's perfectly okay to disagree. But any comment must contain a counterargument to be useful, for example, one could've argued that load is not an issue in a small array and so on, and I may happily accept the other side of the argument. However, I respectfully criticize that your comment doesn't include any counterargument, it's not useful, please read the article more carefully next time.