Date: Tue, 28 Jul 2009 20:30:18 -0700 From: Marcel Moolenaar <xcllnt@mac.com> To: Harald Schmalzbauer <h.schmalzbauer@omnilan.de> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: `gpart show` and secondary GPT header Message-ID: <A6416A11-1D78-41A9-B535-76F4FD512B87@mac.com> In-Reply-To: <4A6F944D.6040909@omnilan.de> References: <permail-200906131853081e86ffa80000190b-a_best01@message-id.uni-muenster.de> <A7C988A9-DCFD-422B-B39D-B912FECEFD0D@mac.com> <4A344A9F.5020708@jrv.org> <BD2A6E6D-EC33-408E-913B-CAF96F774ACD@mac.com> <4A344C67.8000101@jrv.org> <ADAD4EA3-0D07-4CD5-8805-3D21BB40A5AD@mac.com> <4A37C1A7.1070801@omnilan.de> <19563E0A-3A5A-4B0C-BB89-934A44CF4A82@mac.com> <4A6F944D.6040909@omnilan.de>
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On Jul 28, 2009, at 5:14 PM, Harald Schmalzbauer wrote: > Marcel Moolenaar schrieb am 16.06.2009 18:28 (localtime): >> On Jun 16, 2009, at 9:00 AM, Harald Schmalzbauer wrote: >>> Marcel Moolenaar schrieb am 2009-06-14 07:23 (localtime): >>> ... >>>>>>> Jun 13 06:31:42 bigback kernel: GEOM: ad12: the secondary GPT >>>>>>> table is >>>>>>> corrupt or invalid. >>>>>>> Jun 13 06:31:42 bigback kernel: GEOM: ad12: using the primary >>>>>>> only -- >>>>>>> recovery suggested. >>> >>> I'm curious what the correct way to recover is. >>> I also tried dd, but without success. >>> `gpt` had a recover functionality if I remember corretcly. >> Recovery is not yet implemented in gpart. That would be >> the correct way to recover. And yes, gpt(8) has recovery. >> Thus, gpt(8) is the right way to recover on -STABLE. > > Hello, I'd need some help. > I tried to recover the secondary GPT after overwriting on the same > disk. > I used 'dd if=/dev/ada0 iseek=1 count=1 oseek=1953525167 of=/dev/ada0' > I thought this must work since the location of the secondary, stored > in the GPT header, is correct. But it doesn't. The table is also duplicated. Thus, a few LBAs are different. This means the checksum is different. Consequently, you can't simply dd(8) to recover. FYI, -- Marcel Moolenaar xcllnt@mac.com
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