[toast0]

This email doesn't detail the integrity scheme, only that data was protected if no more than two disks failed, and more than two disks failed.

That could be three copies at 3x the storage cost, or it could be a RAID6 or raidz2 style system where the storage cost is essentially two disks out of the storage set size (which we don't know).

You could certainly increase the required failure count by increasing the parity, but if the problem was something like all the disks in the storage system hit the same fatal disk firmware bug at the same time (as speculated elsewhere in the thread, and is unfortunately plausible), then that doesn't really help much.