[solved] no RAID md device nods at startup

sven · 2006-03-28 10:50:32

I am trying to set up Arch on harddrives that are set to RAID-1. The problem is that there are no md nods at /dev. Should I make it so that mkdev md is always called at rc.local or is there some other way? Like some udev rule?

EDIT: There is a line in udev.conf:
# md block devices
KERNEL=="md[0-9]*", NAME="md%n", SYMLINK+="md/%n"

and I have loaded raid1 and raid5 via rc.conf, MODULES array. But this has no effect and no mds are created at boot.

tomk · 2006-03-28 12:36:31

I think you need to set up RAID in your initrd. I'm not sure about that, as I don't have RAID, but there is a RAID section in /etc/mkinitrd.conf.

Moo-Crumpus · 2006-03-28 13:26:52

Depending of your hardware, you may have a hardware Raid that in fact is a kind of bios supported software raid. F.e. the SIL 3112A Sata raid chip is such a thing. For those 'hardware' you would have to setup a software raid. I don't know if this kind of hardware raid is of any use at all.

As I own such a hardware, I decided not to use raid, therefore I can't tell you if real hardware raid would be detected if a mirror ore stripe has been set up. I would presume it would.

Under circumstances, the nodes are just not created, but would be used if you create them manually. Have you tried

mknod /dev/md0 b 9 0

yet before you start the installation? Maybe you'll have to run loaddisk before, to fetch extra modules from the iso image - I remember parts of it are raid tools.

sven · 2006-03-28 17:27:29

tomk, I set the raid part to none (it was 1, disabled). I run mkinitrd after that and now I can see raid info at kernel boot up - so raid is enabled now. I think this is one step to the right direction

Moo-Crumpus, thanks for your tips! I have sometimes wondered how to get Arch install to recognize raid partitions. This motherboard has hardware raid, but I like to have only some partitions joined into raid - because some of the space is good to be used to temporarily store large files - like tv captures. So Linux raid seems better in this case,more configurable. I tried to create mds with mknod, too, as you described, but still they don't hold over the boot and disappear.

Moo-Crumpus · 2006-03-28 18:06:21

If it is a software raid, you must use the raid tools to setup and configure the raid sets. Starting up archlinux installer will not create and use md0 devs then. You have to start the setup of the raid set then, load the modules, and udev will create the nodes on later booting. This is theory for me, afaik you'll find a wiki article about it.

Moo-Crumpus · 2006-03-28 18:07:53

and here it is ... drumroll ...
http://wiki.archlinux.org/index.php/Ins … AID_or_LVM
tada

sven · 2006-03-29 09:47:43

I guess it is something with my config - I still haven't learnt udev enough. Some reading will do good - I'll try to follow the raid guide to the letter and then see how it goes. Better reinstall than hack too much.Those sata drives work real fast - I have got over 60 MB/s some times. Raid-1 on them would be great

Moo-Crumpus · 2006-03-29 13:28:43

Raid 15 would be even nicer - a stripe set, enclosed in a mirror set. Charming. I can't afford that ... sigh.

syamajala · 2006-03-30 02:14:39

dmraid detects raid sets. so, if you setup a raid in the bios and you have dmraid it will automatically create /dev/mapper/omgsomereallylongnamewithnumbers the only distro that i know that has it is fc5. thats what i think it does too i'm not exactly completely sure yet.

sven · 2006-03-31 09:02:55

I got my raid-1 to work now, I followed the guide (http://wiki.archlinux.org/index.php/Ins … AID_or_LVM). Nothing extra was needed for sata drives, just the 0.7.1 full install cd.

I ran into some troubles during that install, but figured those out:
- kernel module dm_mod is not automatically loaded and before the "lvm lvcreate" it must be modprobed or the command won't work
- there is no need to create /sys - dir because it already exists
- using vi or nano was very slow (saving and loading) - I even thought the install froze but vi started to response again
- the comment at the guide's discussion area is still valid because dm_mod is not modprobed at /etc/rc.sysinit

Moo-Crumpus · 2006-03-31 09:20:09

can you change the topic to ....[solved]?

Arch Linux

#1 2006-03-28 10:50:32

[solved] no RAID md device nods at startup

#2 2006-03-28 12:36:31

Re: [solved] no RAID md device nods at startup

#3 2006-03-28 13:26:52

Re: [solved] no RAID md device nods at startup

#4 2006-03-28 17:27:29

Re: [solved] no RAID md device nods at startup

#5 2006-03-28 18:06:21

Re: [solved] no RAID md device nods at startup

#6 2006-03-28 18:07:53

Re: [solved] no RAID md device nods at startup

#7 2006-03-29 09:47:43

Re: [solved] no RAID md device nods at startup

#8 2006-03-29 13:28:43

Re: [solved] no RAID md device nods at startup

#9 2006-03-30 02:14:39

Re: [solved] no RAID md device nods at startup

#10 2006-03-31 09:02:55

Re: [solved] no RAID md device nods at startup

#11 2006-03-31 09:20:09

Re: [solved] no RAID md device nods at startup

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