Partitioning
Johnson David
DavidJohnson at Siemens.com
Tue Jan 13 11:38:30 PST 2004
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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