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From: Michael White <mdwhite@ucdavis.edu>
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: file system HELP HELP HELP
Date: Mon, 15 Jul 1996 13:31:03 -0700
Organization: University of California, Davis
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J Wunsch wrote:
>
> Michael White <mdwhite@ucdavis.edu> wrote:
>
> > Like I said previously, I was able to use the install disk to
> > look at the drive and it looks like there are no partitions anymore.
> > Just one big empty disk.
>
> Partitions? Or slices?
>
> You don't necessarily need fdisk slices... ah, yep, i re-read the
> thread. You used to have two slices on it (curious: why? it doesn't
> buy you very much). Well, your only chances are that you are able to
> remember all the hairy details. If you know how the disk was
> partitioned (by block numbers, or if you did it with sysinstall,
> perhaps by megabytes), it should be possible to put the fdisk table
> and perhaps even labels back into place.
I set it up with sysinstall. The reason I had set up two partitions
was I wanted the /, swap and /usr slices to be under the first 500MB (as
initally I was having install problems... though in hind sight it may
not have been necessary). Also, I am using the terms partitions and
slices as I understood them to be used. Dos/Windows/Linux all require
you use partitions to seperate different filesystems. FreeBSD is able
to allow you to define slices on the disk (thus, you are limited to
4 partitions on a disk, but you may have many more BSD slices). Is this
the incorrect usage of the terms?
> I once had to do this for a
> disk where sector 0 has been trashed by a kernel core dump, and using
> the exact same numbers for a sysinstall run yielded the same results
> and got the disk back to life.
>
> Of course, you need to be careful to stop _before_ sysinstall would
> newfs your partitions.
I think I might have written down the information. How do you stop
before
sysinstall newfs the partitions? (Is this simply quiting without having
it "commit"
>
> If you don't know the previous layout, you might still be able to find
> it the hard way by searching the disk for the disklabel or file system
> magic numbers. The disklabel magic numbers are stored at offset 0x200
> and 0x284 from the beginning of the slice:
>
> 0000200 57 45 56 82 04 00 00 00 73 74 33 36 35 35 6e 00 WEV.....st3655n.
> ^^^^^^^^^^^
> 0000210 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> 0000220 00 00 00 00 00 00 00 00 00 02 00 00 55 00 00 00 ............U...
> 0000230 05 00 00 00 c9 09 00 00 a9 01 00 00 4c 40 10 00 ....É...©...L@..
> 0000240 00 00 00 00 00 00 00 00 94 11 01 00 00 00 00 00 ................
> 0000250 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> *
> 0000280 00 00 00 00 57 45 56 82 dd a7 08 00 00 20 00 00 ....WEV.ݧ... ..
> ^^^^^^^^^^^
>
What program would you recommend I use to search the disklabel?
[stuff deleted]
> --
> cheers, J"org
>
I will try. I suspect I will not be successful though. Oh well, I was
waiting until the next release to get the CDROM's anyway. I guess
instead
of an upgrade, I might have to simply install the new system. By the
way,
any good books on file system structures? (Or magizine articles?)
Thanks for the help you've given so far and for anything you might be
able
to add.
--
- Mike
========================================================================
| |
| _ |
Michael D. White _______|/V\|_______
University of California, Davis X------------[_\(.)/_]------------X
Dept. of Mechanical & Aeronautical Engineering /o`~|~`o\
white@halfdome.engr.ucdavis.edu O H O
http://www.engr.ucdavis.edu/~mdwhite
http://www-mae.engr.ucdavis.edu/CFD/white
========================================================================