access an extended partition and

Polytropon freebsd at
Thu Apr 28 15:22:39 UTC 2011

On Thu, 28 Apr 2011 10:35:10 -0400, Michael Powell <nightrecon at> wrote:
> sofiane chabane wrote:
> > Good morning,
> > I have installed FreeBSD in a multiboot way on my PC but till now I can't
> > access my extended partition. Indeed, on my PC I have 4 primary partitions
> > that I organized like this:
> > 
> > 
> >  Primary partition 1 : WinRE of windows vista
> > 
> >  Primary partition 2 : windows Vista
> > 
> >  Primary partition 3 : FreeBSD
> > 
> >  Primary partition 4 that is the extended one contains:
> > 
> >              Logical partition 1 : windows XP
> > 
> >              Logical partition 2 : a Gnu/Linux distribution
> > 
> >              Logical partition 3 : Data
> > 
> > So, the problem is that I can't access the extended partion especially the
> > Data one. This is my first problem.
> > 
> > The second one is this:
> > I'd like to change my profil picture (on my logging screen-I'm using KDE)
> > and put my personal photo for example; I have tried but kdbm inducates
> > that it 's impossible to do it.

NOTHING is impossible, even if KDE tells you so. :-)

> > These are the problems I've encountered,
> > so I hope I were concise. Thank you very much for being so kind and help
> > me to solve these problems.
> > 
> The so-called Dos 'Extended Partition' begins numbering with ad(x)s5.  It's 
> been so long since I dealt with this. Partitions 'c' is a special 
> designation and 'b' usually is reserved for swap. But a wild guess would be 
> that your logical partition 1 (windows XP) would be ad(x)s5a, [substitute 
> drive number for (x)]  - the next would be ad(x)s5d, and ad(x)s5e (maybe 
> your 'Data' one?). You can manually use the mount command to test mount to 
> somewhere like /mnt before trying to hardcode into fstab, if indeed you even 
> wish to do so.

First of all, you can check partition layout using

	# fdisk ad0

where I assume that ad0 is your first disk which we're
talking about. "DOS extended partitions", as far as I
understood their "concept", do not support the numbering
scheme used in UNIX partitioning, but continue the numbering.
According to Mike's suggestion, I think you will find
the following layout:

ad0s1	= 1st "DOS primary partition" -> WinRE of windows vista
ad0s2	= 2nd "DOS primary partition" -> windows Vista
ad0s3	= 3rd "DOS primary partition" -> FreeBSD
	Layout is something like this:
	ad0s3a = /
	ad0s3b = swap
	ad0s3a = /tmp
	ad0s3e = /var
	ad0s3f = /usr
	ad0s3g = /home
ad0s5	= 1st "logical drive" inside "DOS extended partition"
	-> windows XP
ad0s6	= 2nd "logical drive" inside "DOS extended partition" -> 
	-> a Gnu/Linux distribution
ad0s7	= 3rd "logical drive" inside "DOS extended partition" -> 
	-> Data

Terminology: A slice is what "Windows" calls a "DOS primary
partition", and the "separators" on the slice are partitions.
Also note that a "DOS primary partition" is something different
from a "DOS extended partition" (which contains "logical drives"),
again not the same as partitions (in the UNIX meaning).
A partition carries a file system. For a slice in the
function of a "DOS primary partition", this is implicit,
and the filesystem usually is msdosfs or ntfs. A partition
(again in the UNIX meaning) can have any file system; on
FreeBSD, it's usually UFS. As far as I know, there are
no partitions in a "DOS extended partition" - the "logical
drives" are represented by an own slice each.

The partition letter "c" refers to "the whole slice" or
"the whole drive". I think it is implied since FreeBSD 5,
so /dev/ad0s7 can be used instead of /dev/ad0s7c.

Do not confuse all this confusing stuff. :-)

Try using the mount command (mount_ntfs I assume in your case)
to test-mount the drives (use -o ro for this, just to be sure).

I am not a "multi-booter" and do not use any "Windows",
so I can't be more specific, sorry. Still I hope you can
try something given the above explainations.

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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