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Date:      Tue, 13 Jan 2004 11:36:00 -0800
From:      Johnson David <DavidJohnson@Siemens.com>
To:        Teilhard Knight <teilhk@hotpost.co.uk>, FreeBSD_Newbies <freebsd-newbies@freebsd.org>
Subject:   Re: Partitioning
Message-ID:  <200401131136.01110.DavidJohnson@Siemens.com>
In-Reply-To: <00b701c3d9d6$9c3d2ef0$210110ac@ARLETTE>
References:  <00b701c3d9d6$9c3d2ef0$210110ac@ARLETTE>

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On Tuesday 13 January 2004 05:10 am, Teilhard Knight wrote:
> I am trying to install FreeBSD 5.1. I have created by means other
> than the installation program, a partitioning of my disk (160 Gig),
> and I want to install on one of those partitions. I have three
> primary partitions and one extended where I have installed Linux in
> one logical partition. I want FreeBSD to go in another logical
> partition. When I installed 4.7 in another computer, I had no
> problems whatsoever.

Not possible. FreeBSD must be installed to a primary partition. At the 
minimum, the root filesystem must be installed to a UFS filesystem on a 
primary partition. It might have been possible that you installed to an 
*extended* partition, blowing away any logical partitions underneath.

> But with 5.1 the partitioning utility only sees
> the primary partitions, the first three and the extended one as a
> whole.

That is correct, and by design. FreeBSD uses a different partitioning 
scheme that is not compatible with Microsoft's. IIRC, the original 
design of the PC assumed that each OS would have it's own primary 
partition.

An analogy would be to think of primary partitions as houses, with 
logical partitions as subdividing a house into apartments. FreeBSD is 
not prevented from visiting other houses and apartments, but it must 
reside in its own house. Linux gets away with using Microsoft logical 
partitions because it is a squatter. It is using an empty apartment 
logically owned by another operating system.

> It sees the extended partition as one partition without the
> logical ones created there. Apparently I must have the partition for
> FreeBSD as FAT, but other tools do not help me because the partition
> is too large to be FAT.

FreeBSD must be installed to the partition of type 165, not FAT, NTFS, 
EXT2, or anything else. It can access filesystems on others, but it 
cannot be installed to them.

When you create your primary partitions, you must mark one of them as 
BSD (165). If you are creating them with FreeBSD (or Linux) fdisk, then 
the option is there. But if you are using DOS/Windows fdisk, it doesn't 
know about BSD partitions. So your options are to either leave 
unallocated space, or mark it as FAT remembering which one it is. Then 
during FreeBSD installation, create it or remark it as appropriate.

That huge partition you are seeing is presumably the DOS extended 
partition. During FreeBSD installation, you can only see the primary 
partions, and an extended partition is really a primary partition. If 
you try to install to this extended partitition (by remarking it as a 
BSD partition), you will lose everything in the logical partitions 
underneath.

Another drawback you have to be aware of is that the extended partition 
MUST be the last primary partition. For this and other reasons, I don't 
like extended partitions. With room for four primary partitions, you 
should rarely need an extended partition.

Since this is freebsd-newbies, I cannot give you technical details on 
installation. But as an example only, here is how one possible 
partition layout for a dual boot between Windows and FreeBSD. THIS IS 
ONLY AN EXAMPLE:

1 - primary, NTFS, Windows operating system (ad1s1 under FreeBSD)
2 - primary, BSD (165), FreeBSD operating system (ad1s2)
3 - primary, FAT, shared data partition (ad1s3)

The FreeBSD partition names are given in parenthesis, and these assume a 
single IDE harddrive (not SCSI or SATA).

David



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