Serious dd breakage in current

[Kevin Oberman]

Today I bit the bullet and re-sized some partitions on my laptop's
disk. One think I planned to do was copy the unchanged partitions from
my backup disk to the primary with dd(1). This was a BAD idea and I
suspect GEOM changes are at the root of it.

I used fdisk to create new slices and then bsdlabel to make new
partitions in ad0s2. Everything seemed to be fine.

Then I ran dd to copy the root partition over: dd bs=32k if=/dev/ad2s3a
of=/dev/ad0s2a For some reason it labeled the disk with the first
partition starting at almost the end of the physical partition, over 30
million blocks into the slice. bsdlabel generated a stream of errors
including that every partition extended past the physical partition.

After that, I re-did it all using dump | restore and everything went
fine, if a bit slower.

I don't recall seeing any reports of this, but it was very
unpleasant. Any ideas on what might be the culprit?
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634