(8.3-RELEASE,9.1-BETA) Can't mount the partitions created via 4. 11-RELEASE

[Norihiko Murase]

Dear Mr. Andrey V. Elsukov,

Thank you very much for your comment.


> if i understand correctly, you have bsdlabel's metadata just after MBR,
> and it overlaps MBR (maybe you have configured dangerous dedicated disk?).

Hmm....
I would like to ask several questions about the "dangerous 
dedicated disk", because I haven't heard of it (I did't know
anything about it).

First of all, what is the meaning of this word? Is it the
same as that mentioned at the following web pages?
  * FreeBSD Handbook (7.4-RELEASE) - 18.3 Adding Disks
    http://docs.freebsd.org/doc/7.4-RELEASE/usr/share/doc/en_US.ISO8859-1/books/handbook/disks-adding.html
      > If the disk is going to be truly dedicated to FreeBSD,
      > you can use the dedicated mode.
      ..........
      > In the dedicated case, the drive will be added simply
      > as /dev/da1e.
  * FAQ for FreeBSD 6.X, 7.X and 8.X - 9.3(Will a "dangerously dedicated" disk endanger my health?)
    http://docs.freebsd.org/doc/7.4-RELEASE/usr/share/doc/en_US.ISO8859-1/books/faq/disks.html#DANGEROUSLY-DEDICATED

The "old" HDD that is mentioned at the following e-mail message:
  * URL: http://lists.freebsd.org/pipermail/freebsd-geom/2012-July/005345.html
    Date: Mon, 23 Jul 2012 13:46:58 +0900
    Message-ID: <20120723134658.153fa6c%mur1080224 at inter7.jp>
    To: freebsd-geom at freebsd.org
    From: Norihiko Murase <mur1080224 at inter7.jp>
    Subject: (8.3-RELEASE,9.1-BETA) Can't mount the partitions created via 4. 11-RELEASE
does have 2 slices (FDISK partitions) as follows:
  (1) sysid 165=0xA5 (FreeBSD)
      flag  80 (active)
      start 63, size 14801409 (7227 MB)
      BSD partitions: a, b, c, e, f, g
        - 'a' is for "root" of the 4.11-RELEASE system.
  (2) sysid 165=0xA5 (FreeBSD)
      flag  00
      start 14801472, size 5242608 (2559 MB)
      BSD partitions: c, e
        - 'e' is used for /home
Is this HDD under "dangerous dedicated" mode?

When I did run the live CD of FreeBSD 7.4-RELEASE with this
"old" HDD, I could find the following "ad#c" device nodes
in /dev:
  ad16c
  ad16cs1
  ad16cs1{a,b,c,e,f,g}
  ad16cs2
  ad16cs2{c,e}
as well as the "ad#s*" one
  ad16
  ad16s1
  ad16s1{a,b,c,e,f,g}
  ad16s2
  ad16s2{c,e}
Do these "ad#c" device nodes stem from "dangerous dedicated"
mode??


> You can try backup first 16 sectors and try to overwrite second sector
> (where bsdlabel is) with zeroes. I.e.:
> 
> # dd if=/dev/ada0 of=./backup count=16
> # dd if=/dev/zero of=/dev/ada0 count=1 seek=1
> 
> After that your MBR should appear and you will see ada0s1 and ada0s2.
> If this will not help, or you will get not what you have wanted,
> then you can restore sectors from the backup.

Before I start to erase (overwrite with zeroes) this, does
the following (the dump of the second sector of this "old" HDD)
match what you expect?
------------------------------
Fixit# 
Fixit# dd if=/dev/ad16 count=1 skip=1 | hexdump -C
1+0 records in
1+0 records out
512 bytes transferred in 0.000272 secs (1882107 bytes/sec)
00000000  57 45 56 82 05 00 00 00  77 64 30 73 31 00 00 00  |WEV.....wd0s1...|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000020  00 00 00 00 00 00 00 00  00 02 00 00 3f 00 00 00  |............?...|
00000030  ff 00 00 00 df 04 00 00  c1 3e 00 00 30 d9 31 01  |.........>..0.1.|
00000040  00 00 00 00 00 00 00 00  10 0e 01 00 00 00 00 00  |................|
00000050  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000080  00 00 00 00 57 45 56 82  b4 21 08 00 00 20 00 00  |....WEV..!... ..|
00000090  00 20 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |. ..............|
000000a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
000000b0  00 00 00 00 30 d9 31 01  00 00 00 00 00 00 00 00  |....0.1.........|
000000c0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000200
Fixit# 
Fixit# uname -a
FreeBSD  7.4-RELEASE FreeBSD 7.4-RELEASE #0: Thu Feb 17 03:51:56 UTC 2011     root at walker.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386
Fixit# 
------------------------------


Best regards,
---
Norihiko Murase <mur1080224 at inter7.jp>