fdisk question (long)

From: Ion-Mihai Tetcu (itetcu_at_apropo.ro)
Date: 12/02/03

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Date: Tue, 2 Dec 2003 12:50:44 +0200
To: freebsd-questions@freebsd.org

Hope someone will have the pacince to read all this ...

I have a 120G HDD, in the BIOS is set as LBA. I've RTFM as much as I
could, but there still are some things I clearly don't understand. I
want to be sure that I can move this disk to another machine with
anouter BIOS and the system still boots up.

I've used sysinstall to make partitions and the result is bellow:

it# fdisk ad0
******* Working on device /dev/ad0 *******
parameters extracted from in-core disklabel are:
cylinders=232578 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=232578 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 497952 (243 Meg), flag 0
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 30/ head 254/ sector 63
The data for partition 2 is:
sysid 6 (0x06),(Primary 'big' DOS (>= 32MB))
    start 498015, size 41929650 (20473 Meg), flag 0
        beg: cyl 31/ head 0/ sector 1;
        end: cyl 1023/ head 254/ sector 63
The data for partition 3 is:
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 42427665, size 192008880 (93754 Meg), flag 0
        beg: cyl 1023/ head 255/ sector 63;
        end: cyl 1023/ head 254/ sector 63
The data for partition 4 is:
<UNUSED>

Q1: How can the partition 3 end up before beginning ?

Q2: What is the Warning: BIOS sector numbering starts with sector 1
trying to say ? The cylinders=232578 heads=16 sectors/track=63 shows the
same as in teh BIOS screen.

Q3: The in-core parameters and those for BIOS calculation are the same;
this normal (from my experince) / when they won't mach ?

So i decided to make it by hand (note that sysid 0 for the first
partition is a typo - it should be 165 and I'll want the / slice on it,
and I want to reserve the second partition for a winXP, and the 3rd will
be for the other slices).

I did:

it# fdisk -Biv ad0
******* Working on device /dev/ad0 *******
parameters extracted from in-core disklabel are:
cylinders=232578 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=232578 heads=16 sectors/track=63 (1008 blks/cyl)

Do you want to change our idea of what BIOS thinks ? [n]
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 497952 (243 Meg), flag 0
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 30/ head 254/ sector 63
Do you want to change it? [n] y
Supply a decimal value for "sysid (165=FreeBSD)" [0]
Supply a decimal value for "start" [0]
Supply a decimal value for "size" [0] 497952
Explicitly specify beg/end address ? [n]
sysid 0 (0000),(unused)
    start 0, size 497952 (243 Meg), flag 0
        beg: cyl 0/ head 0/ sector 1;
        end: cyl 493/ head 15/ sector 63
Are we happy with this entry? [n] y
The data for partition 2 is:
sysid 6 (0x06),(Primary 'big' DOS (>= 32MB))
    start 498015, size 41929650 (20473 Meg), flag 0
        beg: cyl 31/ head 0/ sector 1;
        end: cyl 1023/ head 254/ sector 63
Do you want to change it? [n]
The data for partition 3 is:
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 42427665, size 192008880 (93754 Meg), flag 0
        beg: cyl 1023/ head 255/ sector 63;
        end: cyl 1023/ head 254/ sector 63
Do you want to change it? [n] y
Supply a decimal value for "sysid (165=FreeBSD)" [0] 165
Supply a decimal value for "start" [0] 42427665
Supply a decimal value for "size" [0] 192008880
Explicitly specify beg/end address ? [n]
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 42427665, size 192008880 (93754 Meg), flag 0
        beg: cyl 106/ head 15/ sector 1;
        end: cyl 127/ head 14/ sector 63
Are we happy with this entry? [n] y
The data for partition 4 is:
<UNUSED>
Do you want to change it? [n]
Do you want to change the active partition? [n] y
Supply a decimal value for "active partition" [1] 1
Are you happy with this choice [n] y
Do you want to change the boot code? [n] y

We haven't changed the partition table yet. This is your last chance.
parameters extracted from in-core disklabel are:
cylinders=232578 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=232578 heads=16 sectors/track=63 (1008 blks/cyl)

Information from DOS bootblock is:
1: sysid 0 (0000),(unused)
    start 0, size 497952 (243 Meg), flag 80 (active)
        beg: cyl 0/ head 0/ sector 1;
        end: cyl 493/ head 15/ sector 63
2: sysid 6 (0x06),(Primary 'big' DOS (>= 32MB))
    start 498015, size 41929650 (20473 Meg), flag 0
        beg: cyl 31/ head 0/ sector 1;
        end: cyl 1023/ head 254/ sector 63
3: sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 42427665, size 192008880 (93754 Meg), flag 0
        beg: cyl 106/ head 15/ sector 1;
        end: cyl 127/ head 14/ sector 63
4: <UNUSED>
Should we write new partition table? [n] y

Q4: I've supplied the start and size parameters by reading those
provided by the sysinstall partitioning. How can I calculate them ?

Q5: Why the new parameters are different from those of sysinstall ?

Q6: Is this schema OK and will I be able to use this disk in an other
computer and access all the partitions and slices ?

-- 
IOnut
Unregistered ;) FreeBSD user
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Next message: Gary Jennejohn: "Re: ide-scsi emulation required?"

Previous message: anubis: "Re: (Semi)hot swap IDE"
Next in thread: Malcolm Kay: "Re: fdisk question (long)"
Reply: Malcolm Kay: "Re: fdisk question (long)"
Reply: Jerry McAllister: "Re: fdisk question (long)"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

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