Comment 66 for bug 557429

> If one
> port flakes on one boot, the other port flakes on the next, and both ports
> are available on the third, wouldn't that trigger this same bogus
> reassembly?

That depends.

On linux-raid list it was said it would only happen if the event count on both segements are eqal +/-1. That would be the case mostly only if nothing but imediately shutting down is done upon booting of both segments (like in the testcase that driggered this). Different uptimes should be enough to cause a difference in the event count, and prevent this bug from happening.

So there should already be some measure in place that prevents this, for common cases.
What makes this hard to detect and debug is Bug #535417 (mdadm monitoring has been broken in ubuntu).

The suggestion that mdadm should test for conflicts in superblocks (marking each other as failed) should however be able to detect independently degraded segments of an array 100%.