format slice

[Alejandro Pulver]

On Mon, 14 Mar 2005 22:54:57 +0100
"Freek Nossin" <freeknossin at tiscali.nl> wrote:

> 
> 
> > -----Original Message-----
> > From: Alejandro Pulver [mailto:alejandro at varnet.biz]
> > Sent: zondag 13 maart 2005 15:53
> > To: Freek Nossin
> > Cc: freebsd-questions at freebsd.org; 'Jerry McAllister'
> > Subject: Re: format slice
> > 
> > Hello,
> > 
> > Sorry I did not noticed it before, but your first slice must be of
> > type 165 (or 0xa5 in hex), that is the type of FreeBSD slices.
> > 
> > > > The data for partition 1 is:
> > > > sysid 0 (0000),(unused)
> > > >     start 63, size 20820177 (10166 Meg), flag 0
> > > >         beg: cyl 0/ head 1/ sector 1;
> > > >         end: cyl 174/ head 15/ sector 63
> > > > The data for partition 2 is:
> > > > sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
> > > >     start 20820240, size 19201392 (9375 Meg), flag 80 (active)
> > > >         beg: cyl 1023/ head 255/ sector 63;
> > > >         end: cyl 1023/ head 15/ sector 63
> > 
> > It appeares as "unused". So try changing the type.
> > 
> > Best Regards,
> > Ale
> 
> Finally it worked!
> 
> Thanks for helping me (but if I may? Still one question left... ). 
> 
> The slice was indeed unused. When I tried sysinstall just after the
> reboot, and again it didn't worked I falsely assumed doing it from the
> command prompt would also be of no use. I was wrong, following your
> advice, starting fdisk (this time with -i, instead of -u, just to
> figure out if there was any difference, still don't know that yet
> though ;-) ). And changing the type created a freebsd slice. Then I
> used bsdlabel and there it was! /dev/ad0s1a was in my list of devices.
> 
> 
> There is one little thing that worries me. On someone's advice I
> installed testdisk (sysutils/testdisk). This tool tests your disk
> (duh! I mean slices and partitions, so actually my disklayout). 
> 
> Disk /dev/ad0 - CHS 39704 16 63 - 19541 MB
> Check current partition structure
>      Partition                  Start        End    Size in sectors
>  1 P FreeBSD                  0   1  1 20654  15 63   20820177
>  2 * FreeBSD              20655   0  1 39703  15 63   19201392
> 
> Bad starting head
> 
> 
> The "bad starting head" warning worries me. But with these tools you
> never know if the tool is correct, or indeed my disklayout. If I
> didn't just wrote my "Bios Partition table" a couple of times, I
> wouldn't have worried at all, but now I did, it *might* be possible
> that I actually did something wrong. My fdisk output is as follows
> (These numbers come even visit me in my dreams these days... ;-) ):
> 
> bash-2.05b$ sudo fdisk
> ******* Working on device /dev/ad0 *******
> parameters extracted from in-core disklabel are:
> cylinders=39704 heads=16 sectors/track=63 (1008 blks/cyl)
> 
> Figures below won't work with BIOS for partitions not in cyl 1
> parameters to be used for BIOS calculations are:
> cylinders=39704 heads=16 sectors/track=63 (1008 blks/cyl)
> 
> Media sector size is 512
> Warning: BIOS sector numbering starts with sector 1
> Information from DOS bootblock is:
> The data for partition 1 is:
> sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
>     start 63, size 20820177 (10166 Meg), flag 0
>         beg: cyl 0/ head 1/ sector 1;
>         end: cyl 174/ head 15/ sector 63
> The data for partition 2 is:
> sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
>     start 20820240, size 19201392 (9375 Meg), flag 80 (active)
>         beg: cyl 1023/ head 255/ sector 63;
>         end: cyl 1023/ head 15/ sector 63
> The data for partition 3 is:
> <UNUSED>
> The data for partition 4 is:
> <UNUSED>
> 
> Does anybody see a "bad starting head"??? 
> 
> Thanks again for helping me so far (Alejandro, and Jerry)
> 
> Freek
>

Hello,

You are welcome.

Mine is better :)

Disk /dev/ad0 - CHS 77504 16 63 - 38146 MB
Disk /dev/ad2 - CHS 79656 16 63 - 39205 MB

Disk /dev/ad0 - CHS 77504 16 63 - 38146 MB
 1 * FAT32 LBA                0   1  1 36863   6 63   37158282
Bad ending head
 2 E extended LBA         36863   7  1 77488   1 63   40949685
Bad ending head
Disk /dev/ad2 - CHS 79656 16 63 - 39205 MB
 1 P Linux                    0   1  1 20304   5 63   20466747
Bad ending head
 4 * FreeBSD              40624  11  1 79225   4 63   38909430
Bad ending head
TestDisk exited normally.

I do not know what is that, but I think it is just a warning. It has to
do with low level disk parameters (cylinders, heads, sectors, etc.) I do
not know. There is information about that (not specifically this topic
but there is a *lot* of information about hard-disks and how do they
operate) in

http://www.pcguide.com/topic.html (section hard-drives)

but I did not have problems with my slices/filesystems/data.

Best Regards,
Ale