failing raid on shutdown

[Patrick Welche <prlw1%cam.ac.uk@localhost>]

I updated an old box to -current/amd64 (6.99.40) about a fortnight
ago, and noticed that its first root raid0 would fail with an IO
error on shutdown. On startup, reconstructing it to itself seemed
to work.  I just thought the disk was old enough, and should get
a new one.

Today, on an up-to-date -current/amd64 box (recent hardware,
6.99.42), I installed a brand new disk, to mirror from another
reasonably new 2T existing disk. Same again: the new disk's first
root raid0 partition fails with an IO error on shutdown and the
component needs rebuilding.

Coincidence?

Cheers,

Patrick