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From: Kristian Kennaway <kkennawa@physics.adelaide.edu.au>
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Subject: Re: Corrupted disk slice
To: freebsd-questions@freebsd.org
Date: Thu, 24 Apr 1997 02:23:11 +0930 (CST)
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> 
> Wolfgang Helbig <helbig@MX.BA-Stuttgart.De> wrote:
> 
> > Extended partitions are not recognized by our fdisk, so it says it's
> > unused.
> 
> That's not true.  As my inclusion of my 'fdisk' output showed, my extended
> partition is partition 1 (aka slice 2):
> 
> 	The data for partition 1 is:
> 	sysid 5,(Extended DOS)
> 		start 1048320, size 3144960 (1535 Meg), flag 0
> 			beg: cyl 130/ sector 1/ head 0;
> 			end: cyl 519/ sector 63/ head 127
> 
> > If you build a file system on slice four, it is overlaid by the extended
> > partition and the logical partitions inside the extended partition.
> 
> No - there is nothing magic about slice four.  (this is all on a 2.1.5R
> system, but I'm pretty sure I've seen the same thing on earlier versions)

Okay, so what you are saying is that the fact that I had a freebsd 
partition on wd1s4, with dos partitions on wd1s1 and wd1s5, could not 
have been the single cause of the now-missing partition? Since sysinstall 
was the one who decided to put my partition on wd1s4, I'd think this is 
the case.

The following may help:

[morden] 1:46 ~ fdisk wd1
******* Working on device /dev/rwd1 *******
parameters extracted from in-core disklabel are:
cylinders=621 heads=128 sectors/track=63 (8064 blks/cyl)

parameters to be used for BIOS calculations are:
cylinders=621 heads=128 sectors/track=63 (8064 blks/cyl)

Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 0 is:
sysid 6,(Primary 'big' DOS (> 32MB))
    start 63, size 2048193 (1000 Meg), flag 0
        beg: cyl 0/ sector 1/ head 1;
        end: cyl 253/ sector 63/ head 127
The data for partition 1 is:
sysid 5,(Extended DOS)
    start 2048256, size 2048256 (1000 Meg), flag 0
        beg: cyl 254/ sector 1/ head 0;
        end: cyl 507/ sector 63/ head 127
The data for partition 2 is:
sysid 165,(FreeBSD/NetBSD/386BSD)
    start 4096512, size 911232 (444 Meg), flag 80
        beg: cyl 508/ sector 1/ head 0;
        end: cyl 620/ sector 63/ head 127
The data for partition 3 is:
<UNUSED>

I'm assuminbg partition 3 here is the one which I used to have but no 
longer do. partition 1 is on wd1s5, 2 is on wd1s3.

Trying to disklabel the invalid partition gives me this:

[morden] 1:54 /dev disklabel -r rwd1s4e
disklabel: /dev/rwd1s4e: Invalid argument

and likewise with the other slices on this partition.

Kristian