Does this comparison include filesystem reserve?
Yes. The comparison table applies a 10% reserve baseline to reflect realistic operating headroom in NAS and homelab environments.
Can two layouts with similar available space still have very different rebuild risk?
Yes. Similar usable TB does not imply similar failure tolerance or rebuild exposure. Capacity and resiliency should be evaluated together.
How should I select between RAID-Z2 and RAID 6?
Choose based on your risk tolerance, rebuild window, and performance profile. Higher parity usually lowers capacity but improves resilience.
Which has more usable storage headroom: RAID-Z2 or RAID 6?
For US homelab buyers, this NAS planning scenario compares both modes at fixed drive sizes so you can see usable capacity differences before buying disks.