Date: Mon, 11 Mar 1996 19:00:19 +0100 (MET) From: "Christoph P. Kukulies" <kuku@gilberto.physik.rwth-aachen.de> To: imb@scgt.oz.au (michael butler) Cc: hackers@FreeBSD.org Subject: Re: Clobbered partititon table .. :-( Message-ID: <199603111800.TAA09773@gilberto.physik.rwth-aachen.de> In-Reply-To: <199603111602.DAA12008@asstdc.scgt.oz.au>
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>
>
> How does one recover from the clobbered partition table that no longer
> exists after you try to install another drive with the 2.1 install disk ?
>
> michael
>
It happened to me, more than once. Once is ok, but twice is stupidity :-)
The program below (dirty hack) scans the disk for a FS_MAGIC.
Once found you can dd skip=n count=m if=/dev/rwd0 of=file
the disk to a file (provided you have enough space)
and do a
vnconfig /dev/vn0 file
mount /dev/vn0 /mnt
and recover the data.
You can even fsck /dev/vn0 first.
BTW, tar'ing a file from a vn device to a nfs mounted FS paniced
2.1 (reproducable).
--Chris Christoph P. U. Kukulies kuku@gil.physik.rwth-aachen.de
#include <stdio.h>
#include <sys/types.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/param.h>
#define DKTYPENAMES
#include <sys/disklabel.h>
#include <ufs/ffs/fs.h>
/*
*/
#define DISKMAGIC ((u_long) 0x82564557) /* The disk magic number */
main(argc,argv)
int argc;
char **argv;
{
int i;
char *dev;
struct fs *f;
struct disklabel *dl;
struct stat sb;
off_t lseek();
off_t block=0;
char buf[2048];
off_t end;
u_long *l;
off_t offset = (off_t) 0;
off_t newoffset;
int ofd,fd, vd, n;
if(argc==2)
dev=argv[1];
else
dev="/dev/rwd0";
printf("sizeof struct fs=%d\n",sizeof(struct fs));
l = (u_long *) buf;
f = (struct fs *) buf;
dl = (struct disklabel *) buf;
if ((fd = open(dev, O_RDONLY, 0)) == -1)
fprintf(stderr,"error opening %s\n",dev),exit(1);
if ((ofd = open("/mnt/dump", O_CREAT|O_WRONLY, 0666)) == -1)
fprintf(stderr,"error opening %s\n","/mnt/dump"),exit(1);
while(read(fd, buf, 2048)>0) {
write(ofd,buf,2048);
block+=2048;
/* printf("\r%qd",block);fflush(stdout);*/
if (*l == DISKMAGIC) {
printf("\ndisklabel found at offset %qd (%qd MB/%qd)\n",
block-2048, (block-2048)/ (off_t) (1024), (block-2048) / 2048);
printf("d_type=%d\n%s\nd_npartitions=%d\n", dl->d_type,
dl->d_typename,
dl->d_npartitions);
for (i = 0; i < dl->d_npartitions; i++) {
printf("\t%d\t%d\t%d\t%s\n",
dl->d_partitions[i].p_size,
dl->d_partitions[i].p_offset,
dl->d_partitions[i].p_fsize,
fstypenames[dl->d_partitions[i].p_fstype]);
}
}
if(f->fs_magic == FS_MAGIC )
printf("fs at block # %qd last mounted on %s f->fs_ncyl=%ld
(%d %d %d = %d)\n",(block-2048)/512,
f->fs_fsmnt,
f->fs_ncyl,
f->fs_ntrak, /* tracks per cylinder */
f->fs_nsect, /* sectors per track */
f->fs_spc , f->fs_spc*f->fs_ncyl /* sectors per cylinder */);
}
}
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