Bug 174593 – kernel needs to know raid multi divice layout to boot. Add to the guide

• Product: [OLD] Docs on www.gentoo.org
• Status: RESOLVED WORKSFORME

[Description Mark R. de Rooij 2007-04-14 14:38:18 UTC]

I have used the above Guide, but in the end it doesn't work. Like
others I had the problem " cannot open root device md3". The solution
is on your forums: Let the kernel know your md3 layout in grub

kernel /boot/kernel root=/dev/md3 md=3,/dev/sda3,/dev/sdb3

Maybe it is worth putting it in the guide

Reproducible: Always

Steps to Reproduce:
1. Follow the guide with liveCD 2006.1 and AMD64 proccessor
2. Don't use ssh, but use the LiveCD and stay behind your box
3. reboot

Actual Results:  
Kernel Panic " cannot open root device md3 "

Expected Results:  
complete to boot

[Comment 1 nm (RETIRED) 2007-04-14 15:43:37 UTC]

I've had no such troubles following this guide to install Gentoo on my AMD64 (RAID1), nor do I need that extra weird line in grub.conf.

All that's needed is  root=/dev/md3

The guide does work ('ve tested it twice); it sounds more like you might have made a mistake in setting up mdadm.

[Comment 2 SpanKY 2007-04-14 17:18:01 UTC]

mdadm is a userspace process; kernel unable to find root is a kernel issue

my guess would be you didnt create your raid devices with raid autodetect so the kernel on booting up doesnt automatically detect your raid setup

[Comment 3 IBA 2009-10-29 03:23:48 UTC]

the gentoo short install guide advises to use kernel parameter
root=/dev/md3

however, this requires particular changes to the kernel during make menuconfig in  /usr/src/linux  . Otherwise the above problem will be reproduced.

suggestion: provide working kernel configuration that supports non-RAID systems.

the boot problem is not a bug, it is merely a user unfiendly configuration.

[Comment 4 IBA 2009-10-29 03:32:25 UTC]

during make menuconfig, ensure that your SATA drivers and automount capability is enabled. The preconfigured kernel config has most drivers not enabled.