Date: Sun, 2 Jan 2011 01:15:35 -0500 From: Chris Brennan <xaero@xaerolimit.net> To: Ian Smith <smithi@nimnet.asn.au> Cc: freebsd-questions@freebsd.org Subject: Re: a new hard-drive in a 2y/o laptop Message-ID: <AANLkTikbEVXu%2BmUY3i9vY9cGhfeDPHtjx5tarhzYXvrz@mail.gmail.com> In-Reply-To: <20110102130224.O49334@sola.nimnet.asn.au> References: <20110101033922.BBE051065783@hub.freebsd.org> <20110102130224.O49334@sola.nimnet.asn.au>
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On Sat, Jan 1, 2011 at 10:20 PM, Ian Smith <smithi@nimnet.asn.au> wrote: > Well, what's commonly called 'the partition table' is bytes 0x1be-1ff of > the MBR, so I was confused by your writing to sector 1 rather than 0, > but have a new theory to test, seeing Chris isn't making any progress; > this maybe a victim of the old 'slice vs partition' terminology issue. > > I think I was able to figure this part out, his meaning at least. > The bsdlabel lives in sector 1 (counting from 0) of the slice concerned, > specifically the first 0x114 (276d) bytes, in the second sector of the > boot blocks. As noted above, in unsliced disks such as memstick.img > that's sector 1 of the entire disk, but in ordinary sliced disks it's in > sector 1 of the _slice_, so if you'd used (here using Chris' ad4) > > dd if=/dev/zero of=/dev/ad4s1 oseek=1 bs=512 count=1 > > I would happily run this, but ad4s1 doesn't exist, and hasn't (that I know of), I did do oseek=0 and oseek=1 on /dev/ad4 tho and that didn't change anything, it still says it can't find /dev/ad4s1b (swap obviously) > - rather than of=/dev/ad4 - then you would indeed be zeroing out the > label, ie the 'partition table' in FreeBSD-speak. Is that perhaps what > you had to do to that 6.2 disk, which I suppose was a sliced disk? > > At 6.x (and 7.x, I think) it could have been 'dangerously dedicated' ie > unsliced .. which option has been removed in 8.x _except_ regarding the > memstick.img (appearing as /dev/daXa) .. not half confusing, eh? > > I actually noticed this today, I had issues writing 8.2BETA1 to a 2GB MicroSD card, so I used a 2.5" external hard-drive and from the fixit prompt I noticed that it wrote a 1gb partition for the BETA1 image and left the rest of the desk untouched (ann 59gb of it). > In any case, it'd be a cheap trick for Chris to try from Fixit, and > though it seems unlikely there'd be anything 'leftover' from an earlier > install, maybe earlier failure/s have left a broken bsdlabel there? > > So at this still-uninstalled stage it couldn't hurt to zero that sector, > or even the first 4KB of ad4s1 .. which is /boot/boot1 plus /boot/boot2 > (which equals /boot/boot !) before the label section gets written. ie: > > sysctl kern.geom.debugflags=16 > dd if=/dev/zero of=/dev/ad4s1 bs=512 count=8 > > will remove slice 1's boot blocks entirely, including the bsdlabel. > > cheers, Ian > > [excuse broken threading, but unless cc'd I have to reply to the digest] > I've been trying to keep you in my replies but your down-under, so I don't get your replies till after 1am my time... Anywho, it's late and I need to be up in 8hrs, hopefully this can be figured out ... I would hate for the disk to be defective in some way.
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