Metadata on raid1 doesn't guarantee the resilience to two-drive failures that raid6 is used for, but metadata on raid1c3 does give you that degree of resilience

Metadata on raid1 doesn't guarantee the resilience to two-drive failures that raid6 is used for, but metadata on raid1c3 does give you that degree of resilience (with more space overhead, but that's seldom a problem for the metadata).