Re: [gentoo-user] Dual Boot Partitions

[Mick <michaelkintzios@gmail.com>]

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On Sunday 27 February 2011 18:04:26 Florian Philipp wrote:
> Am 27.02.2011 17:02, schrieb Petri Rosenström:
> > On Sun, Feb 27, 2011 at 5:01 PM, dhk <dhkuhl@optonline.net> wrote:

> >> First, the observations.  I tried to partition my disk with fdisk the
> >> way I wanted.  

I would recommend you use 'parted -a optimal' or gparted for this purpose (see 
below).


> >> It had the usual Linux partitions and a partition that I
> >> was going to use for Window 7.  I wanted to make this an LVM2 partition,
> >> but that didn't work; I guess that was too ambitious.

I am not sure that you can use LVM2 for MSWindows - as far as I know they use 
Logical Disk Manager which it is not the same with any other sane LVM 
implementation - come on now, would you expect them to seek compatibility or 
interoperability?!!

http://en.wikipedia.org/wiki/Logical_Disk_Manager

> >> Then I just made
> >> it an ordinary static HPFS/NTFS partition on /dev/sda5.  When installing
> >> Windows 7 it wouldn't install on that partition.  I deleted all the
> >> partitions and just installed it on the first 50Gigs of the disk.
> >> 
> >> Second, the questions.  The Windows 7 install on the first 50Gigs of the
> >> disk needed to created two partitions.  The first was a very small boot
> >> partition that I increased to 128Megs, and the second is the rest of
> >> Windows 7.  Now when I boot to the livecd to partition the rest of the
> >> disk for Gentoo fdisk says "Partition 1 does not end on a cylinder
> >> boundary."  Is this a problem?  The other big question is:  what do I do
> > 
> > Dunno, it might be that win7 changed the amount of heads/sectors that
> > could give that notice from fdisk. I would not be to worrified about
> > it (Installing windows would be more horrifying). If you have a
> > traditional hd then the worst thing I think might be that reads/writes
> > would be slower.
> 
> If I'm not mistaken, this alignment is actually a good thing. It is
> related to the transition from 512 B blocks to 4 kB and also helps
> alignments for SSDs. In this regard, Win 7 behaves very clever and
> really much better than the old and proven Linux tools (unless you know
> what you are doing and are aware of every issue). IMHO it is a real
> shame that most Linux tools are still behind in this regard.

Only some are.

The 'parted -a optimal' or gparted will seek to align the end of a partition, 
but you will find that it may under/overshoot your specified size to achieve 
that.

fdisk et al have some development to do yet.


> If you think you have an HDD with 4kB blocks, ask and I can provide you
> with some links on that topic.
> 
> >> about the first partition in the partition table?  It is an HPFS/NTFS
> >> partition and has been toggled bootable.  It also has some stuff in it
> >> that looks like it's important to Windows:  a BOOTSECT.BAK file, a Boot
> >> directory, a System Volume Information directory, and a bootmgr file.
> >> Now for my Gentoo install, how and where do I make a /boot partition?
> >> Do I replace the Windows 7 boot partition with /boot?  If so, what
> >> happens to the contents?  or Do I make a /boot partition on /dev/sda3
> >> and toggle the bootable flag there?
> > 
> > Something like that. You could install gentoo on one partition (I
> > don't recommend).

No!  Nothing like that.  Leave the MS Windows boot partition alone and flagged 
as boot.  MS Windows needs this, while Linux does not.


> > Just make partitions like you would do without windows. When you do
> > the grub-install script or by hand grub links the boot to the
> > partition where boot exists. You should not remove or change the
> > windows partitions or the data windows will probably brake when you
> > do.

Yep.  Create a new partition; e.g. /dev/sda3 and use that as the /boot 
mountpoint for your Linux OS.  This is where the grub fs, Linux OS kernels and 
related files will be saved.


> AFAIK, grub does not need the bootable flag. Leave it alone. Maybe
> Windows needs it, maybe it is just for good measure, I don't know.

This is correct, MS Windows needs it and it will not boot without it, 
especially if you retain the MSWindows MBR boot code - although you can 
install GRUB in the MBR and chainload MSWindows from there with it.

HTH.
-- 
Regards,
Mick

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