[9fans] Really weird SATA disk/controller issue

["Devon H. O'Dell" <devon.odell@gmail.com>]

Hey all,

That laptop that I was boasting ran Plan 9 flawlessly (minus the
non-native graphics) is now exhibiting some really weird behavior.
I've replaced the old Hitachi Travelstar disk (100GB / 7200RPM) with a
Seagate 320GB disk (5400RPM). I can install FreeBSD and CentOS fine.
When I try to install Plan 9 onto this new disk, I get really weird
I/O errors now. If I try to delete labels / partitions, it goes wacky
with I/O errors on what seems to be the second disk operation I do
from the menu, with a caveat:

o If I go from a blank disk, I can get to copydist before it gives me
an I/O error on every block copy.
o If I go from a disk that had a failed install, I can delete the
labels (9fat, nvram, fossil, swap), but if I then try to delete the
partition, I get an I/O error. Sometimes I can get to fmtfossil from
here, but that will always give me an I/O error if I start from this
state.
o If I go from a disk that had a failed install, and delete the
partitions, I try to delete labels later, I get an I/O error when
trying to write the labels.

It still works fine on the old 100GB disk.

I've experimented with various sizes, and installing it after other
operating systems, to no avail.

Why should the disk matter?

--dho