Electrical surges or component aging destroy the physical RAID controller hardware, leaving the configuration metadata unreadable.
(Can recover directly from any single mirror drive) RAID 5 Block striping with distributed parity 1 Drive (Can operate in a degraded state) High (Can be virtually rebuilt even if missing one drive) RAID 6 Block striping with dual distributed parity 2 Drives (Can operate in a degraded state) High (Can be virtually rebuilt even if missing two drives) RAID 10 Mirrored sets that are striped together 1 Drive per mirrored pair ufs raid recovery