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From: John Murphy <sub02@freeode.co.uk>
To: freebsd-questions@freebsd.org
Date: Tue, 14 Mar 2006 00:31:37 +0000
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Subject: Using 'incorrect' HD geometry.
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I'm currently dual booting FreeBSD-5.3 and Windows 2000 on a WD800BB
80GB IDE HD.  It all seems to be working very well, but now I want to
install 6.0 on the slice where 5.3 is.  fdisk -s currently says:

/dev/ad0: 155061 cyl  16 hd  63 sec

Part     Start       Size   Type  Flags
  1:        63    5981220   0x0b   0x00
  2:   5981283   13971447   0xa5   0x80
  3:  19958400  136337040   0x0f   0x00

The problem is that the installer says that geometry of 155061/16/63
is incorrect and suggests using the BIOS geometry of 38309/16/255.

I'm worried that if I change the geometry I may lose the existing
Win2k slices (1 and 3 in the fdisk output).  I'm not even convinced
that what the BIOS says is correct, as I get the following from other
sources:

16383/16/63   from the Western Digital web site.
10337/240/63  probed values from Scisoft Sandra.
10337/240/63     "      "     "  Ranish Partition Manager.

If I make sure the installer uses the existing incorrect geometry,
does that guarantee that the other slices will be unaffected?

What future problems may that lead to?

-- 
John.