Arch Linux

kikinovak

Member

From: Montpezat (South France)

Registered: 2005-12-07

Posts: 96

Website

Trouble getting software RAID1 to boot

Hi,

I'm currently trying to install Arch on two harddisks using software RAID1. I used these two docs as a starting point for inspiration :

1) https://wiki.archlinux.org/index.php/In … igure_Arch
2) https://wiki.archlinux.org/index.php/Co … Using_raid

I add that I'm used to configure similar setups on CentOS (my current workhorse distro at work). But I'm quite new to Arch.

Here's how I go about it.

1) I boot the install CD and immediately load the RAID1 module :

# modprobe raid1

2) Then I launch cfdisk and partition the two disks similarly with FD type partitions.

3) I create the three RAID devices:

# mdadm --create /dev/md1 --level=1 --raid-devices=2 --metadata=0.90 /dev/sda1 /dev/sdb1
# mdadm --create /dev/md2 --level=1 --raid-devices=2 --metadata=0.90 /dev/sda2 /dev/sdb2
# mdadm --create /dev/md3 --level=1 --raid-devices=2 --metadata=0.90 /dev/sda3 /dev/sdb3

4) I take a peek in /proc/mdstat, where everything seems fine.

5) I launch the installer:

# /arch/setup

4) I choose to manually mount the various devices, which appear correctly as /dev/md1 (/boot, ext2), /dev/md2 (swap) and /dev/md3 (root partition, ext4).

5) When editing /etc/mkinitcpio.conf, I have:

MODULES=(raid1)
...
HOOKS=(... ... mdadm filesystems)

6) I install GRUB on each MBR (that is, sda AND sdb).

Upon rebooting, after a short while, I get the following error message:

Root device '/dev/md3' doesn't exist. Attempting to create it. 
ERROR: Unable to determine major/minor number of root device '/dev/md3'.

Any idea what I forgot here?

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Dyslexics have more fnu.

kikinovak

Member

From: Montpezat (South France)

Registered: 2005-12-07

Posts: 96

Website

Re: Trouble getting software RAID1 to boot

I went back through the procedure, and indeed found out I forgot something important before running mkinitcpio:

# mdadm --examine --scan > /mnt/etc/mdadm.conf

Now everything works like a charm.

---

Dyslexics have more fnu.

kikinovak

Member

From: Montpezat (South France)

Registered: 2005-12-07

Posts: 96

Website

Re: Trouble getting software RAID1 to boot

Post scriptum. Now everything seems to work fine... except I just wasted three unnerving hours trying to find out why I'm getting the same "Assembling RAID arrays... FAIL" message on startup. Only to stumble over this bug report dating from February : https://bugs.archlinux.org/task/18440.

Is this a WONTFIX or a DONTCARE?

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Dyslexics have more fnu.