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Date:      Mon, 29 Dec 2008 11:05:03 +0100
From:      "David Scialom" <dscialom@gmail.com>
To:        Tim <tajudd@gmail.com>, freebsd-questions@freebsd.org
Subject:   Re: Unable to modify sysid with Fdisk
Message-ID:  <c4a0126f0812290205g3e2f4572l84c74116c6c95eed@mail.gmail.com>
In-Reply-To: <4957E333.1050103@gmail.com>
References:  <c4a0126f0812280845q5bcab455u70d07038aa0b27e2@mail.gmail.com> <4957E333.1050103@gmail.com>

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Hello Tim,

Thanks for your suggestion. The probleme after the section 3 does not exist.
It is actually a wrong copy paste done by me. Nothing changed after your
suggestion :

Zurich# dd if=/dev/zero bs=512 count=128 of=/dev/da0
128+0 records in
128+0 records out
65536 bytes transferred in 0.095998 secs (682681 bytes/sec)

Zurich# fdisk -u da0
******* Working on device /dev/da0 *******
parameters extracted from in-core disklabel are:
cylinders=8 heads=64 sectors/track=32 (2048 blks/cyl)

parameters to be used for BIOS calculations are:
cylinders=8 heads=64 sectors/track=32 (2048 blks/cyl)

Do you want to change our idea of what BIOS thinks ? [n]
*fdisk: invalid fdisk partition table found*
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 32, size 16352 (7 Meg), flag 80 (active)
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 7/ head 63/ sector 32
Do you want to change it? [n] y
Supply a decimal value for "sysid (165=FreeBSD)" [165] 12
Supply a decimal value for "start" [32]
Supply a decimal value for "size" [16352]
Explicitly specify beg/end address ? [n]
sysid 12 (0x0c),(DOS or Windows 95 with 32 bit FAT (LBA))
    start 32, size 16352 (7 Meg), flag 80 (active)
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 7/ head 63/ sector 32
Are we happy with this entry? [n] y
The data for partition 2 is:
<UNUSED>
Do you want to change it? [n]
The data for partition 3 is:
<UNUSED>
Do you want to change it? [n]
The data for partition 4 is:
<UNUSED>
Do you want to change it? [n]
Partition 1 is marked active
Do you want to change the active partition? [n]

We haven't changed the partition table yet.  This is your last chance.
parameters extracted from in-core disklabel are:
cylinders=8 heads=64 sectors/track=32 (2048 blks/cyl)

parameters to be used for BIOS calculations are:
cylinders=8 heads=64 sectors/track=32 (2048 blks/cyl)

Information from DOS bootblock is:
1: sysid 12 (0x0c),(DOS or Windows 95 with 32 bit FAT (LBA))
    start 32, size 16352 (7 Meg), flag 80 (active)
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 7/ head 63/ sector 32
2: <UNUSED>
3: <UNUSED>
4: <UNUSED>
Should we write new partition table? [n] y
*fdisk: Geom not found: "da0"*

Zurich# fdisk da0
******* Working on device /dev/da0 *******
parameters extracted from in-core disklabel are:
cylinders=8 heads=64 sectors/track=32 (2048 blks/cyl)

parameters to be used for BIOS calculations are:
cylinders=8 heads=64 sectors/track=32 (2048 blks/cyl)

fdisk: invalid fdisk partition table found
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 32, size 16352 (7 Meg), flag 80 (active)
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 7/ head 63/ sector 32
The data for partition 2 is:
<UNUSED>
The data for partition 3 is:
<UNUSED>
The data for partition 4 is:
<UNUSED>





2008/12/28 Tim <tajudd@gmail.com>

> David Scialom wrote:
>
>> Hello,
>>
>> It seems that it  is impossible to modify the sysid with fdisk since
>> FreeBSD
>> 6.2. I am actually using FreeBSD7.0.
>> When I want to modify my the sysid from 165(ufs) to 12(Fat32) i get the
>> message "Geom not found: da0" and no change is made: da0 is stock with
>> sysid
>> = 165. The detail are provided below. I tried also to do the same from the
>> install FreeBSD CD without success.
>>
>> As someone a solution ?
>>
>> Zurich# fdisk -u da0
>> ******* Working on device /dev/da0 *******
>> parameters extracted from in-core disklabel are:
>> cylinders=1009 heads=64 sectors/track=32 (2048 blks/cyl)
>>
>> parameters to be used for BIOS calculations are:
>> cylinders=1009 heads=64 sectors/track=32 (2048 blks/cyl)
>>
>> Do you want to change our idea of what BIOS thinks ? [n]
>> *fdisk: invalid fdisk partition table found*
>> 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 32, size 2066400 (1008 Meg), flag 80 (active)
>>        beg: cyl 0/ head 1/ sector 1;
>>        end: cyl 1008/ head 63/ sector 32
>> Do you want to change it? [n] y
>> Supply a decimal value for "sysid (165=FreeBSD)" [165] 12
>> Supply a decimal value for "start" [32]
>> Susysid 12 (0x0c),(DOS or Windows 95 with 32 bit FAT (LBA))
>>    start 32, size 2066400 (1008 Meg), flag 80 (active)
>>        beg: cyl 0/ head 1/ sector 1;
>>        end: cyl 1008/ head 63/ sector 32
>> Are we happy with this entry? [n] y
>> The data for partition 2 is:
>> <UNUSED>
>> Do you want to change it? [n]
>> The data for partition 3 is:
>> <UNUSED>
>> Supply a decimal value for "size" [2066400]
>> Explicitly specify beg/end address ? [n]
>> sysid 12 (0x0c),(DOS or Windows 95 with 32 bit FAT (LBA))
>>    start 32, size 2066400 (1008 Meg), flag 80 (active)
>>        beg: cyl 0/ head 1/ sector 1;
>>        end: cyl 1008/ head 63/ sector 32
>> Are we happy with this entry? [n] y
>> The data for partition 2 is:
>> <UNUSED>
>> Do you want to change it? [n]
>> The data for partition 3 is:
>> <UNUSED>
>> Do you want to change it? [n]
>> The data for partition 4 is:
>> <UNUSED>
>> Do you want to change it? [n]
>> Partition 1 is marked active
>> Do you want to change the active partition? [n] y
>> Supply a decimal value for "active partition" [1]
>> Are you happy with this choice [n] y
>>
>> We haven't changed the partition table yet.  This is your last chance.
>> parameters extracted from in-core disklabel are:
>> cylinders=1009 heads=64 sectors/track=32 (2048 blks/cyl)
>>
>> parameters to be used for BIOS calculations are:
>> cylinders=1009 heads=64 sectors/track=32 (2048 blks/cyl)
>>
>> Information from DOS bootblock is:
>> 1: sysid 12 (0x0c),(DOS or Windows 95 with 32 bit FAT (LBA))
>>    start 32, size 2066400 (1008 Meg), flag 80 (active)
>>        beg: cyl 0/ head 1/ sector 1;
>>        end: cyl 1008/ head 63/ sector 32
>> 2: <UNUSED>
>> 3: <UNUSED>
>> 4: <UNUSED>
>> Should we write new partition table? [n] y
>> fdisk: Geom not found: "da0"
>> Zurich# fdisk da0
>> ******* Working on device /dev/da0 *******
>> parameters extracted from in-core disklabel are:
>> cylinders=1009 heads=64 sectors/track=32 (2048 blks/cyl)
>>
>> parameters to be used for BIOS calculations are:
>> cylinders=1009 heads=64 sectors/track=32 (2048 blks/cyl)
>>
>> fdisk: invalid fdisk partition table found
>> 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 32, size 2066400 (1008 Meg), flag 80 (active)
>>        beg: cyl 0/ head 1/ sector 1;
>>        end: cyl 1008/ head 63/ sector 32
>> The data for partition 2 is:
>> <UNUSED>
>> The data for partition 3 is:
>> <UNUSED>
>> The data for partition 4 is:
>> <UNUSE
>>
>>
>
> The "Warning: Invalid fdisk partition table found" is a red flag to me.  If
> the partition boundries don't lie on a cylinder, than it's invalid.
>
> I also see after it prints partition 3, it randomly asks for the size of
> the partition, without asking for anything else.
>
> I think those first 512 sectors are messed up.  If I were you, I'd wipe the
> first 2 tracks of the disk.
> dd if=/dev/zero bs=512 count=128 of=/dev/da0
>
> And recreate the partition then.  fdisk isn't seeing a sane layout to begin
> with and it may silently be discarding the changes asked.
>
> Good luck.
>



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