Date: Mon, 17 Feb 1997 11:23:15 -0500 (EST) From: Lee Cremeans <lee@yakko.my.domain> To: avalon@coombs.anu.edu.au (Darren Reed) Cc: freebsd-hackers@freebsd.org Subject: Re: File system/disk recovery tools ? Message-ID: <199702171623.LAA01016@yakko.my.domain> In-Reply-To: <199702171523.HAA21329@freefall.freebsd.org> from "Darren Reed" at Feb 18, 97 02:17:07 am
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> > In some mail from Christoph Kukulies, sie said: > > > > > Luigi Rizzo stands accused of saying: > > > > > dd the whole disk off onto a file and mount it on a vnode? You might > > > > > > > > unfortunately is 1.6GB ... I need to find a bigger unit! > > > > > > dd bits of it at a time? 8) > > > > > > > > have to reconstruct the label and such, and using fsck's '-b' option > > > > > > > > actually an annoying thing with fsck -b is that I never know what > > > > to use as an alternate superblock number. 32, says the manpage, is > > > > an alternate superblock, but what are others ? I guess they depend > > > > upon the geometry of the disk... is there a "magic" number that I > > > > can look for ? > > > > > > You mean you didn't write them down when you made your filesystems? 8) > > > > > > Ok, presumably your disklabel is OK. Have a look in /sys/ufs/ffs/fs.h > > > at the superblock layout; it's 8K long, has a fixed checksum, and > > > contains various predictable fields (eg. the last mountpoint). This > > > should let you hunt a copy of it down. > > > > Some time ago I wrote a (really quick and dirty) little program which scanned > > the disk for once existing file systems. > > > > It's too dirty to post in public but if anyone wants it I'll > > send it. At least one case beside of my own is known to have been > > successful. > > I've written one of these too (SunOS4) and my comments are the same :-) > (btw, it worked too :-) > > > Bottomline is that you scan the disk for a FS magic and then with the > > obtained data (offset and size) you do a dd skip= count= to a file which > > then can be used as /dev/vn0 to be mounted and files can be restored > > from there. > > Does dumpfs exist on FreeBSD ? > > Yup. I've used it before. Lee C. (and yes, my hostname is bogus...I'm using dynamic IP, and don't want to pay for name service :( )
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