Date: Sat, 24 Nov 2012 08:28:08 -0700 (MST) From: Warren Block <wblock@wonkity.com> To: freebsd@johnea.net Cc: freebsd-questions@freebsd.org Subject: Re: Should newfs include -S 4096? was Re: boot problem after freebsd-update from 9.1-RC2 to 9.1-RC3 Message-ID: <alpine.BSF.2.00.1211240815590.13869@wonkity.com> In-Reply-To: <50AFB42F.2000805@johnea.net> References: <50ABE97B.5030408@johnea.net> <50AC041A.7050607@dreamchaser.org> <50AC3116.6010600@johnea.net> <alpine.BSF.2.00.1211202201460.42121@wonkity.com> <50AFB42F.2000805@johnea.net>
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On Fri, 23 Nov 2012, freebsd@johnea.net wrote: > One of the complications was getting old metadata off of the drive. After trying a couple of 'dd' invocations: > # overwriting the first sector > dd if=/dev/zero of=/dev/ada0 bs=512 count=1 > # also tried overwriting the last sector > diskinfo ada0 | cut -f4 > 3907029168 > (subtract 34, per WB) (I actually just subtracted the trailing 68) > dd if=/dev/zero of=/dev/ada0 seek=3907029100 > > This would still seem to not delete all of the metadata, since after issuing: > > gmirror label -b split gm0 /dev/ada0 > gmirror load > # repartition new mirror > gpart create -s MBR mirror/gm0 > # ignore "mirror/gm0s1 added, but partition is not aligned on 4096 bytes" after add > gpart add -t freebsd -a 4k mirror/gm0 > # create the bsdlabel partitions in slice 1 (s1) > gpart create -s BSD mirror/gm0s1 > > I would see that the old gm0s1a and gm0s1b had reappeared, even though I had not yet issued the 'add -t freebsd-ufs'. I'm not sure if they came back with the 'add -t freebsd' or the 'create -s BSD'. Saved this since yesterday, thinking maybe I could come up with an idea, but so far I can't think what would cause that. It might not hurt to force a retaste after the dd. > The only thing that seemed to fix it was: > > gpart destroy -F /dev/ada0 > > I also tried at one point: > > gpart destroy -F ada0 > gpart create -s gpt ada0 > gpart destroy -F ada0 > The thing I wonder about now: Should newfs include -S 4096? > > I used: > > newfs -U /dev/mirror/gm0s1a > > Will this lead to 512 byte sector access to the disk through the file system? > > Will this impact performance or longevity of the mirror? It's a good question; I have not tried it.
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