said by Jahntassa:I don't think there's a RAID 5+1 controller if that's what you're asking (dual matching RAID 5 arrays in a mirror).
I also don't think there are any hardware RAID controllers that will support RAID5 mirrored onto a single non-RAID drive.
I guess you could layer software RAID 1 on top of the hardware RAID5 and the single disk...But I imagine you would take a pretty ugly performance hit, not to mention creating "complicated plumbing"