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#1 2011-03-05 23:51:53

wes
Member
Registered: 2011-03-05
Posts: 67

dual boot windows 7+archlinux on separate disks; grub errors. [solved]

Hello,

I am very excited to try arch linux, but am having trouble with the
installation.  My situation is as follows:  I have 3 hard drives: windows 7
lives on sda and sdb.  I am installing arch on sdc, which is 500GB.

I partitioned the hard drive as follows (which may look kind of ridiculous,
but please understand I am new at this):

sdc1    /boot    1GB    ext2
sdc2    swap    8GB     swap
sdc3    /       50GB    ext3
sdc4    /home   400+GB  ext3



After some initial issues, I managed to run the installation program
smoothly, performed the basic configuration, and then went to install grub. I
scrutinized the grub menu.lst file over and over, and could not find anything
wrong.  It had the following entry for archlinux:

title: Arch Linux
root: (hd2,0)
kernel: /vmlinuz26 root=/dev/sdc3 ro
initrd: /kernel26.img

There is no entry for windows, as I can just use the BIOS boot menu to switch
between the two bootable hard disks, or at least that was my plan...

When I boot to windows, everything works just fine.  When I go to the
BIOS boot menu and choose to boot from the third disk, I get the grub
bootloader with choices of arch and arch fallback, just as expected. 
I select the former, and I get the following message from grub:

************
Booting 'Arch Linux'

root    hd(2,0)
Filesystem type unknown, partition type 0x7
kernel /vmlinuz26 root=/dev/sdc3 ro

Error17: cannot mount selected partition
************


The same thing happens for the fallback image.  I made very sure to install
grub to the mbr, /dev/sdc.

I have also tried to use the UUID entry for /root in the menu.lst file, and
this gives the exact same results.  I have also run grub interactively from
the bootable CD image, and it does not give such errors-  it knows that
hd(2,0) has type 82, and not 7.  However, when I try the initrd command in
interactive grub, I get a complaint about the image not fitting in memory.
However, I have 16GB of ram...

One other note that may be (but probably is not) relevant:  initially I could
not get the Arch disk to recognize the hard drive (the format disk phase of
installation would always fail), so from windows, I went to the disk manager
and formatted it with ntfs.  This enabled me to format the disk from the arch
install process and install the new FS.  I didn't think the temporary presence
of ntfs would be any kind of an issue since I immediately reformatted it.


Many thanks for your time reading this.  Much appreciated.

Last edited by wes (2011-03-07 21:24:44)

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#2 2011-03-06 00:50:10

stqn
Member
Registered: 2010-03-19
Posts: 1,191
Website

Re: dual boot windows 7+archlinux on separate disks; grub errors. [solved]

I think that if you change your bios settings to boot from your third drive, then it becomes the first disk as far as grub is concerned, which would be "hd(0,0)".

Id 7 is NTFS, which makes sense: if hd0 is your Linux disk, then hd1 and hd2 are your windows ones.

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#3 2011-03-06 01:14:34

wes
Member
Registered: 2011-03-05
Posts: 67

Re: dual boot windows 7+archlinux on separate disks; grub errors. [solved]

That sounds promising... it would also explain why grub is not confused when I run it from the CD.  I just left work, but I'll try it again tomorrow with the grub root set as hd(0,0).  Thanks!

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#4 2011-03-07 18:04:04

wes
Member
Registered: 2011-03-05
Posts: 67

Re: dual boot windows 7+archlinux on separate disks; grub errors. [solved]

stqn-  thanks so much!!!  Worked perfectly by setting the grub root as hd(0,0).  Now I will be able to sleep again 8D

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#5 2011-03-07 19:12:09

stqn
Member
Registered: 2010-03-19
Posts: 1,191
Website

Re: dual boot windows 7+archlinux on separate disks; grub errors. [solved]

Ah ah smile great. Glad to have helped.

Edit: please mark as [solved] by editing the topic of your first post!

Last edited by stqn (2011-03-07 19:12:56)

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#6 2011-03-10 07:39:14

YAOMTC
Member
Registered: 2010-02-23
Posts: 204

Re: dual boot windows 7+archlinux on separate disks; grub errors. [solved]

Oh hey, this helped me too. When I change the boot order in the BIOS, the mapping does in fact change as well. This needs to be documented somewhere!

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#7 2011-03-10 19:17:04

wes
Member
Registered: 2011-03-05
Posts: 67

Re: dual boot windows 7+archlinux on separate disks; grub errors. [solved]

I guess here:

https://wiki.archlinux.org/index.php/Be … Bootloader

or here

https://wiki.archlinux.org/index.php/Wi … ard_Drives

would be sensible places, but as a complete rookie, I don't feel qualified to start editing the wiki...

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