You are not logged in.

#1 2005-04-02 09:27:55

leo.pisolo
Member
Registered: 2004-08-25
Posts: 16

RAID 1. Something I don't understand

Hi to all,
quite long time back I asked a few directios about RAID1 and meanwhile I read all RAID1 posts and also this link:
http://wiki2.archlinux.org/index.php/In … d-or%20LVM

The PC where I'm trying to setup RAID1 is this:
P3-733
Primary Master : SEAGATE 40G ATA (/dev/discs/disc0)
Primary Slave : SEAGATE 40G ATA (/dev/discs/disc1)
Secondary Master : QUANTUM 20G ATA (/dev/discs/disc2)
Secondary Master : CDROM

The boot (by bios) is on Secondary Master (QUANTUM 20G) that is also the Linux Arch installation hard disk + GRUB.
Till here all is okay, installed Arch, updated,upgraded, etc..

When it's time to setup a RAID something go wrong.

First of all, I read that Wombat (0.7) comes with MDADM but this is not true because by default comes with RAIDTOOLS.
So I 'pacman -R raidtools' & 'pacman -S mdadm'.

I add 'mdadm' as daemon in rc.conf and reboot (to be sure that all is loaded smoothly).

I went to partition the 2xSEAGATE with a single partition (max size) with CFDISK.
I went to create the array RAID1 as follow :
'mdadm --create /dev/md/0 --level=1 --raid-devices=2 /dev/discs/disc[01]/part1'
And all went okay.
I check 'cat /proc/mdstat' and found the array in syncronization phase.

I had plenty time to wait up to the end of the sync. (just to be sure).
I make a filesystem on the array 'mke2fs -j /dev/md/0' and all went okay.
I mounted the new filesystem on '/mnt', created an empty file 'EXAMPLE' and umounted.
I mounted/unmounted a few times, before to reboot.

Here come the surprise:
After reboot the 'mdadm' daemon is running but when I try to mount '/dev/md/0' on '/mnt' cannot find a valid filesystem.
I checked '/proc/mdstat' but it return me empty (no array)
I checked '/etc/mdadm.conf' but there is no mention about array (suppose to be added automatically).

In short words, the raid array remain OK till the reboot.
If I create the array and mount, it works great.
But I reboot the PC, there is no more sign of array!

I tried with kernel 2.6.11-3-ARCH (ide), same (scsi) and also with a customized recompiled with 3 same results!

Where do I mistake ?
Thank you
P.

Offline

#2 2005-04-02 13:34:16

FUBAR
Member
From: Belgium
Registered: 2004-12-08
Posts: 1,029
Website

Re: RAID 1. Something I don't understand

I've been using LSR (Linux Software RAID) with Arch for a while now and it's never given me any trouble: I don't even know how that works since all I have to do is make sure the md module and the appropriate module for your RAID-type (in my case raid0.ko) is loaded: when these are compiled into the kernel, the md-module automagically finds my RAID-partitions and starts the correct md-devices in /dev.
I don't have any md-daemon running (I didn't even know there was one until I read your post).
And still everything just works.

What I think you need to do is repartition both of your RAID-1 discs and make sure your partition's type is "Linux raid autodetect" (type fd). Once you've done that, create the md-device and put a filesystem on it. Edit /etc/rc.conf and put "md" and "raid1" in the list of modules to be loaded at boottime, get rid of the mdadm service since it doesn't exist anyway.

Now after rebooting, once the RAID-modules are loaded they should detect and start up your RAID-array automagically. Check this with dmesg.


A bus station is where a bus stops.
A train station is where a train stops.
On my desk I have a workstation.

Offline

#3 2005-04-02 16:29:32

leo.pisolo
Member
Registered: 2004-08-25
Posts: 16

Re: RAID 1. Something I don't understand

Hi FUBAR
really thank you! It works great and happy with that.

What I want to understand is how you get to know that MD is the module, and  WHY raidtools/mdadm is shipped/installed with wonbat if they are not (it seems) so  necessary.

Just curios because without your post (even if I read all your post about RAID here in forum) I was blind and lost!
I never imagined that it could be solved like this...

Offline

#4 2005-04-02 21:15:15

FUBAR
Member
From: Belgium
Registered: 2004-12-08
Posts: 1,029
Website

Re: RAID 1. Something I don't understand

Hehe, great that you got it working. Do a

pacman -Ql raidtools

It provides tools to diagnose and test RAID-arrays I think. Never really used it tho.


A bus station is where a bus stops.
A train station is where a train stops.
On my desk I have a workstation.

Offline

Board footer

Powered by FluxBB