Date: Tue, 15 Jan 2002 12:30:43 -0600 From: "Mike Meyer" <mwm-dated-1011551443.80cdfb@mired.org> To: Annelise Anderson <andrsn@andrsn.stanford.edu> Cc: Alex.Wilkinson@dsto.defence.gov.au, freebsd-questions@FreeBSD.ORG Subject: Re: Super Block Message-ID: <15428.30035.136131.19101@guru.mired.org> In-Reply-To: <Pine.BSF.4.10.10201142256490.53039-100000@andrsn.stanford.edu> References: <15427.39528.11439.547654@guru.mired.org> <Pine.BSF.4.10.10201142256490.53039-100000@andrsn.stanford.edu>
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Annelise Anderson <andrsn@andrsn.stanford.edu> types: > On Mon, 14 Jan 2002, Mike Meyer wrote: > > One-sentence summary of why it's important: It where you start when > > you want to find a file in the file system. > Suppose you overwrite a disklabel and haven't made a copy; if you > can access the slice and you want to write a new disklabel, is > there any way to find out where the superblocks are? Since you don't know the exact sizes, the only way I can think of is to open the raw disk device, read in struct fs sized chunks at block intervals, and check fs_magic for "real" superblocks. When you find a pair that's 32 blocks apart, you've found the superblock and the first alternate for a file system. <mike -- Mike Meyer <mwm@mired.org> http://www.mired.org/home/mwm/ Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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