RAID6, which provides two drives worth of parity compared to RAID5's single drive worth of parity, is the most common successor, especially in hardware (ASIC) i

RAID6, which provides two drives worth of parity compared to RAID5's single drive worth of parity, is the most common successor, especially in hardware (ASIC) implementations. Other examples are ZFS's RAID-Z, which can support even more parity for even more resiliency to drive failure. Contrary to a sibling comment, RAID1+0 does not supersede RAID5, as it has existed at least as long and has always had different trade-offs. How many drive failures one may need to be able to survive, given historical drive failure rates [1], current drive capacity vs. transfer rates (i.e. minimum rebuild time), and individual parameters (e.g. number of drives per array, acceptable magnitude of performance degradation during rebuild), is left as an exercise to the reader. As the OC suggested, this number can still be 1 (i.e. RAID5) for SSDs. [1] optionally including or excluding "black swan" events such as the flooding in Thailand that wiped out thos disk factories, rendering an entire "generation" of HDDs, manufactured in haste elsewhere, far less reliable