Arch Linux

whoop

Member

Registered: 2009-05-28

Posts: 101

Arch linux full raid

I am experimenting with arch and mdadm I was using the following guide:
http://linux-101.org/howto/arch-linux-s … tion-guide

I get into trouble (at least I notice it at that point) with the bootloader. find /boot/grub/stage1 returns Error 15: File not found, so running the commands:
grub> device (hd0) /dev/sda
grub> root (hd0,0)
grub> setup (hd0)

naturally result in the same problem.

Any indication what I am doing wrong? Maybe the tutorial is out of date?

whoop

Member

Registered: 2009-05-28

Posts: 101

Re: Arch linux full raid

OK, so that guide didn't say I had to chroot and I got allot further than before...

Then again int the guide it says:

Install to sda

grub> device (hd0) /dev/sda
grub> root (hd0,0)
grub> setup (hd0)

Install to sdb

grub> device (hd0) /dev/sdb
grub> root (hd0,0)
grub> setup (hd0)

shouldn't this be

Install to sda

grub> device (hd0) /dev/sda
grub> root (hd0,0)
grub> setup (hd0)

Install to sdb

grub> device (hd1) /dev/sdb
grub> root (hd1,0)
grub> setup (hd1)

lilsirecho

Veteran

Registered: 2003-10-24

Posts: 5,000

Re: Arch linux full raid

There are differences in GRUB and Grub2. 

Check the wiki for those diffs.

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whoop

Member

Registered: 2009-05-28

Posts: 101

Re: Arch linux full raid

There are differences in GRUB and Grub2. 

Check the wiki for those diffs.

I understand. I am using GRUB, But I still think:

Install to sda

grub> device (hd0) /dev/sda
grub> root (hd0,0)
grub> setup (hd0)

Install to sdb

grub> device (hd0) /dev/sdb
grub> root (hd0,0)
grub> setup (hd0)

Is an error in the guide because it makes no sense to me installing grub twice on hd0

jasonwryan

Anarchist

From: .nz

Registered: 2009-05-09

Posts: 30,424

Website

Re: Arch linux full raid

You have two drives in your raid array - you want them to be a mirror (assuming you are talking about Raid1); therefore you want grub installed to the same place on each of the drives, no?

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Blµb

Member

Registered: 2008-02-10

Posts: 224

Re: Arch linux full raid

I think you're missing that 'device (hd0) /dev/sdX defines hd0 to be /dev/sdX, which is once done for sda and then for sdb.

I'm curious about the md= entries in this guide though. Is the goal of this to not require mdassemble to be run in an initramfs? Because mdadm usually reads from /etc/mdadm.com in the initramfs to assemble the devices.
But what do I know, mdassemble segfaults for my intel imsm raid... so I'm still sticking to DM-raid though maybe this could help... and that doesn't help me in my case either (says "bad raid superblock magic")

Last edited by Blµb (2012-02-29 09:38:37)

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whoop

Member

Registered: 2009-05-28

Posts: 101

Re: Arch linux full raid

I think you're missing that 'device (hd0) /dev/sdX defines hd0 to be /dev/sdX, which is once done for sda and then for sdb.

Yes I was/am missing that. I understand what you are saying and you have a point but I still have something daunting:
find /grub/stage1
(hd0,0)
(hd1,0) <---- what's this?

running the guide grub installs went fine but running:
grub> device (hd1) /dev/sdb
grub> root (hd1,0)
grub> setup (h1)
also works. Why?

I only have two harddisks installed, what is (hd1) as I was under the impression that it was /dev/sdb, which now seems to be incorrect...

Very confusing..

I'm curious about the md= entries in this guide though. Is the goal of this to not require mdassemble to be run in an initramfs? Because mdadm usually reads from /etc/mdadm.com in the initramfs to assemble the devices.
But what do I know, mdassemble segfaults for my intel imsm raid... so I'm still sticking to DM-raid though maybe this could help... and that doesn't help me in my case either (says "bad raid superblock magic")

You are referring to the "md=" in grub's menu.lst? I also remember this happening in a later stage. The strange thing is that it seems to work though... If you know a better/other guide/tutorial about this subject I would like to know about it.

Thanks allot for the information!

Last edited by whoop (2012-02-29 20:24:30)