RAID 10, originally called RAID 1 + 0, uses striping for increased size
and speed and mirroring for reliability. RAID 10 is a RAID 0 group
that has been mirrored onto another group. Each individual disk in the
RAID 0 group is mirrored. Since mirroring is RAID 1, the joke is that
this is 1 + 0, or 10. Rebuilds on a RAID 10 system are not as disruptive to
performance as rebuilds on a RAID 5 system. As with RAID 1, multiple
mirrors are possible and are commonly used.