Okay, stupid sysadmin-type-that-failed-kernel-hacking-101 question:

If you do a dd from a raw disk and output to either a raw disk or some other
suitable device (such as /dev/null), don't you bypass the buffer cache?

[looking below, I know that's not what he's asking about, but I'm curious
 nonetheless, as I don't know the answer.]

On Wed, 12 Jun 2002, Manuel Bouyer wrote:

# OK, I newfs an old linux partition (which doesn't boot any more anyway).
# doing a cp on the same disk as the system disk freeze X until the
# cp is done.  Same result if I use dd instead of cp.
# Either reading or writing a large file cause this problem (dd if=file
# of=/dev/null, or dd if=/dev/zero of=file)
#
# Has anyone idea of what is causing this ?
# I suspect it could be disksort, which cause a single request to one end of
# the disk be delayed to group dozen of requests on the other end of the disk.


				--*greywolf;
--
NetBSD: the cathedral versus the bizarre.