Nick Guenther wrote:
>
> On 5/6/06, Tony Abernethy <[EMAIL PROTECTED]> wrote:
> > Me, I'd take a closer look at that j OpenBSD partition.
> > It does NOT look like it corresponds to anything in the DOS partitions.
> > Whether or not you redo the disklabel from scratch,
> > the critical operation is writing the disklabel back.
> > This is a place where any slipup, any typo, can do incredible damage.
> > (This is from somebody who LIKES to play with overlapping partitions;)
>
> $ sudo fdisk wd0
> Password:
> Disk: wd0       geometry: 4864/255/63 [78140160 Sectors]
> Offset: 0       Signature: 0xAA55
>         Starting       Ending       LBA Info:
>  #: id    C   H  S -    C   H  S [       start:      size   ]
> ------------------------------------------------------------------------
>  0: 12    0   1  1 -  382 254 63 [          63:     6152832 ] Compaq Diag.
>  1: 0C  383   0  1 - 2597 254 63 [     6152895:    35583975 ] Win95 FAT32L
> *2: A6 2598   0  1 - 3930 254 63 [    41736870:    21414645 ] OpenBSD
>  3: 0C 3931   0  1 - 4862 254 63 [    63151515:    14972580 ] Win95 FAT32L
>
> 16 partitions:
> #             size        offset  fstype [fsize bsize  cpg]
>  a:      20761146      41736870  4.2BSD   2048 16384  328 # Cyl
> 41405*- 62001
>  b:        653499      62498016    swap                   # Cyl
> 62002 - 62650*
>  c:      78140160             0  unused      0     0      # Cyl
>   0 - 77519
>  i:       6152832            63 unknown                   # Cyl
>   0*-  6104*
>  j:      35583975       6152895   MSDOS                   # Cyl
> 6104*- 41405*
>
>
>  j is the same as partition 1, the windows install.

You're right.
Getting cross-eyed in my old age.

> > >
> > >       Then create the mount point directory that you want this
> > > filesystem on,
> > > if you haven't already done so, then edit your fstab with
> your favorite
> > > editor.  Copy and put the mount line from the existing FAT filesystem,
> > > then edit the copy's mount directory and slice entries to match the
> > > slice you defined (in this example, "wd0k").
> > >
> > >       Then reboot to test your changes. Yeah, you could do a "mount
> > > /mount_point", but it's better to reboot to make sure you get your
> > > changes on the next reboot now than when it's really inconvenient
> > > to do so.
> > >
> > > > So long as you are only messing with the disklabel you shouldn't be
> > > > able to destroy your data (well, data on the windows drives
> at least)
> > >  >
> > >       This is misleading.  The OpenBSD disklabel is EVERYTHING to
> > > that OS,
> > > you screw it up, game over.  It is very possible to toast a FAT32 if
> > > you don't get the disklabel set up right.  Anytime you mod the i386
> > > partition table or the disklabel assume you might toast EVERYTHING on
> > > the drive.  That is, have backups, especially if you're learning
> > > this stuff.
>
> True, misleading. I was thinking "you shouldn't be able to actually
> destroy any data [so long as you realize your mistake in time]"
Critical words.
realize.
in time.

>
> > > Then again, if the OP only adds one line, rather than rekey the WHOLE
> > > DISKLABEL as you are suggesting, this shouldn't be a problem
> to OpenBSD.
> > >
>
> Right, that was stupid of me.

However, even if the edit is done with just a single line,
there is something to be said for relaying out the label from scratch.

You get a lot of real problems from "But I didn't change anything"
Best advice on this kind of stuff probably from Nick Holland.
Treat filesystem layout etc stuff with a lot of respect.
There are ways it can bite you in places you never knew you had places.
Operating Systems tend to have error-recovery mechanisms.
Probably fairly easy to set up something that will work perfectly
until the error-recover mechanisms come into play. And then the
code that is supposed to correct stuff actually wrecks the joint.
This kind of code is diabolically hard to test.

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