Date: Fri, 31 Dec 2010 19:37:10 -0500 From: Michael Powell <nightrecon@hotmail.com> To: freebsd-questions@freebsd.org Subject: Re: a new hard-drive in a 2y/o laptop Message-ID: <iflspm$nuc$1@dough.gmane.org> References: <20101229120038.3DFB0106591A@hub.freebsd.org> <20101230133126.O36121@sola.nimnet.asn.au>
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Ian Smith wrote: > In freebsd-questions Digest, Vol 343, Issue 5, Message: 10 > On Tue, 28 Dec 2010 11:02:45 -0500 Chris Brennan <xaero@xaerolimit.net> > wrote: > > On Tue, Dec 28, 2010 at 2:23 AM, Michael Powell > > <nightrecon@hotmail.com>wrote: > > > > > Try zeroing out the mbr: > > > > > > Boot a LiveFS CD, then at a root prompt do: > > > > > > sysctl kern.geom.debugflags=16 and: > > > > > > dd if=/dev/zero of=/dev/adx oseek=1 bs=512 count=1 > > > > > > where x equals your drive number. This will zero out any old MBR. > > Er, no, Mike. The MBR is in sector 0 of the disk; that would zero out > sector 1 as oseek=1 skips over sector 0. What's in sector 1 depends on > how/whether the disk is sliced. In a 'dangerously dedicated' (unsliced) > disk like a memory stick perhaps, this would usually be /boot/boot1 and > include the bsdlabel. In a sliced disk, sectors 1 to 62 are typically > unused, the first slice usually starting at sector 63. > > t23% fdisk -s ad0 > /dev/ad0: 232581 cyl 16 hd 63 sec > Part Start Size Type Flags > 1: 63 8385867 0x0b 0x00 > 2: 8385930 125821080 0xa5 0x80 > 3: 134207010 33543342 0xa5 0x00 > 4: 167750730 66685815 0xa5 0x00 > > If you really want to zero out sector 0, leave out the oseek (or use > oseek=0) - but you're better off using 'fdisk -Bi' to init a new disk. > Yes - true enough. Was thinking partition table and typed 'mbr'. > Mmm .. it's not clear from Chris' original message exactly what he did. In my case, a temporary replacement disk had FreeBSD 6.2 on it. Something changed wrt to disklabeling on the way to 8-Release and the old 6.2 being present created a situation where that region on the disk was invisible to the new labeling and wouldn't write out. A new install of 8-Release (sysinstall) would error out with the same message as Chris when it came to the point of writing out to the disk. For me, the above 2 commands fixed my situation. Even though his error is the same, I think his problem may be different from mine. -Mike [snip]
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