On amd64, recent kernels, I get:

	# savecore -z /var/crash
	savecore: /netbsd: kvm_openfiles: /dev/wd0b: Device busy

I even tried booting an install CD, mounting wd0a, and
running /mnt/rescure/savecore, but it complained that it couldn't find
device 33/950318.  (Aside: shouldn't savecore have an option to point
to the dump device that was used?)

I'm running now without swap, in the hope that I can somehow save that
file -- I have 3GB, so I should be able to last for a while...

		--Steve Bellovin, http://www.cs.columbia.edu/~smb