Installing Windows & Linux on new T105

[Ben Scott]

On Sat, Mar 1, 2008 at 11:28 PM, Timothy Murphy <gayleard at eircom.net> wrote:
> As far as I can see, the first partition contains Dell utilities.
> I assume that it is intended for some kind of repair or rescue?

  As others have said, this is the "Dell utility partition".  It
mainly contains Dell's diagnostic software.  It saves you from having
to find/make a boot CD containing the Dell diagnostics if you run into
hardware failures.  It has partition type 0xDE.  The Dell BIOS has a
non-standard feature that lets you boot this partition by pressing
certain keys during POST (Power On Self Test), and/or as a separate
option on the "Select boot device" menu.

>  The second partition seems to be a kind of vestigial operating system.
>  Windows describes it as "OS (C:)".
>  Windows was installed on /dev/sda5, or LOCAL DISK (E:) according to Windows.

  "sda5" is a Logical Partition, which must be contained within an
Extended Partition.  The IBM-PC standard boot scheme can only boot a
Primary Partition on the first Fixed Disk.  When you told Windows to
install to a Logical Partition, it still had to install its boot
loader (NTLDR and friends) into a Primary Partition so it could boot.
That's what you're seeing as "C:" or "sda2".

  Wit the standard IBM-PC scheme, the BIOS loads the MBR (Master Boot
Record -- the first sector on the disk) from the first Fixed Disk, and
looks for a boot signature.  If the BIOS finds the signature, it
assumes the MBR contains a bootstrap program and attempts to execute
it.  Said program looks at the Partition Table -- also stored in the
MBR -- for an Active Primary Partition.  If it finds one, it loads the
PBR (Partition Boot Record -- the first sector of the partition) and
attempts to execute it.  The code in the PBR is responsible for
loading the operating system.

  Most Linux systems replace the standard MBR bootstrap routine with
something else, like LILO or GRUB.  These programs can do non-standard
things, like boot an OS contained in a Logical Partition or on another
Fixed Disk.    This is one of the rare instances where Linux is
actually doing something non-standard, and Microsoft is following
established convention.

  Windows isn't aware of LILO or GRUB doing these non-standard things,
and so it still assumes the Windows OS loader must be on a Primary
Partition to be bootable.

>  I want to know if I can safely delete /dev/sda2
>  or else copy it to the second 250GB disk?

  If you delete the Primary Partition, your installed copy of Windows
will no longer be able to start, since you'll have deleted its loader.

  What you can do is delete sda5 (the main Windows partition) and sda2
(the "C:" Windows boot partition), and then re-install Windows from
scratch in a single, primary partition (such as sda2, which will be
"C:").

  I've heard talk of ways to coerce Windows into booting and running
from a Logical Partition, without needing a Primary Partition at all,
but they're not supported by Microsoft and may cause you grief at some
point in the future (say, an OS upgrade).  I'd avoid them.

>  Could I also move /dev/sda1 to the second disk?

  I know it is possible to have LILO or GRUB chain to the Dell utility
partition and boot it, so it may be possible to move the Dell
utilities to the second disk and still have it work.  Or it may fail
miserably; it would depend on whether the Dell utility partition's
operating system cares what partition it was started from.  If you do
this, the BIOS feature that lets you boot into the utility partition
from the POST menu will no longer work.

  Given that we're talking about only 50 MiB, I generally just leave
it be.  If you need the partition table entry, or if it just offends
you, I would suggest simply deleting the Dell utility partition
entirely and plan on booting from CD if you need to.

>  Assuming /dev/sda1 must remain where it is,
>  I would like to delete /dev/sda2 and /dev/sda3,
>  and create 30GB Windows partition at /dev/sda2,
>  100MB Linux /boot partition at /dev/sda3,
>  and 30GB Linux / at /dev/sda5 .

  That's basically what I do, and it works very well.  I also
typically tell the Linux loader (GRUB, LILO, etc.) to install into the
Linux boot partition's PBR (/dev/sda3 in your example), rather than
the system-wide MBR (/dev/sda).  That means Linux will behave as a
standard OS, and won't be disabled if another OS re-installs the
standard MBR.  IBM and Microsoft OSes, in particular, always
re-install the standard MBR during their installation routines.

-- Ben