Beyond ~4 large drives, prefer RAID 6 over RAID 5 — rebuilds are when second failures strike.
A rebuild reads every sector of every surviving disk for hours under stress. With multi-TB drives, the odds of hitting an unrecoverable error mid-rebuild stop being negligible.
Not if you can restore quickly from elsewhere: with a fast, tested backup, RAID 5 plus that backup can beat RAID 6 alone. And for SSDs the rebuild window is short enough that the second-failure argument weakens considerably — the rule is really about rebuild time, not drive count.
Estimate with the rule, then check it against the calculator that models it properly.
Open RAID Calculator →Beyond ~4 large drives, prefer RAID 6 over RAID 5 — rebuilds are when second failures strike. A rebuild reads every sector of every surviving disk for hours under stress.