Arch Linux

Jagged

Member

From: Blacksburg, VA

Registered: 2003-07-18

Posts: 153

Neat Stuff: HOWTO install archlinux on a software raid

I had switched back to gentoo after using arch. But after I got lost in my /etc dir looking for crap that was messed up with etc-update, im back on archlinux.

Which brings me to a problem.  I was running gentoo on software raid-0's.  Arch doesn't support installing to raid devices in the ncurses install program.

Simple solution:
1) make like you're installing gentoo.
For instance, my system had two hdd's with four partitions
hda1 - ext3 /boot
hda2,3,4 - to be used for raids
hdb1 - swap
hdb2,3,4 - to be used for raids

hda2 and hdb2 were a raid-0 /dev/md/0 of type reiserfs... to be used for /
hda3 and hdb3 were a raid-0 /dev/md/1 of type reiserfs... to be used for /usr
hda4 and hdb4 were a linear raid /dev/md2 of type XFS (had to be converted to reiser because its not supported on the arch kernel)... to be used for /home

The archlinux install program installs via a chroot to /mnt
So, therefore we mount all of our devices around /mnt like:
mount -t reiserfs /dev/md/0 /mnt
mkdir /mnt/{boot,home,usr}
mount -t ext3 /dev/discs/disc0/part1 /mnt/boot
mount -t reiserfs /dev/md/1 /mnt/usr
mount -t reiserfs /dev/md/2 /mnt/home

then /arch/setup .... and just skip the hdd setup bit.

Note about linux software raid:  It would probably be best to set up the raid before you go to install archlinux.  I'm not sure if the archlinux install cd has all the raidtools available.

Easiest way to setup a software raid:
Get a gentoo basic boot cd (~70 MB)
boot it up
use fdisk and partition your hdd's (make sure to use the 0xFD id for the raid partitions... that way kernels can autodetect the raid)
create an /etc/raidtab to specify how you want the raid setup
mknod /dev/md0 b 9 0
mkraid /dev/md0 (and for anything else you need)
then format the raid device like:
mkfs.xfs /dev/md0

now your raid is setup and good to go... as long as you boot a kernel with automounter and RAID support, it will autodetect it
you can specify a raid device as a root partition during bootup

for instance: my grub line looks like:
kernel /linux-2.4.22-ck2 root=/dev/md/0 ro

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Nkawtg...n!

nifan

Member

Registered: 2003-04-10

Posts: 102

Re: Neat Stuff: HOWTO install archlinux on a software raid

TRAITOR!!

i'm curious about software raid.
what are the advantages to the "normal user" ?
does it have a superb performance?

thnkx for the explanation in advance

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______
"Ignorance, the root and the stem of every evil." - Plato

zen_guerrilla

Member

From: Greece

Registered: 2002-12-22

Posts: 259

Re: Neat Stuff: HOWTO install archlinux on a software raid

I'm not sure if the archlinux install cd has all the raidtools available.

Unfortunately it doesn't (it would be a nice addition for 0.6 along with lvm, apeiro ), however the bundled kernel has support for raid & lvm. A 'quick-n-dirty' solution would be to untar raidtools (and/or lvm) pkg on a floppy, boot arch install cd, mount the floppy, 'export PATH=$PATH:/WHERE/FD/IS/MOUNTED/usr/bin', create /etc/raidtab, mkraid /dev/mdXX, continue as you describe.
I haven't tried it yet, I plan to make a root-on-lvm-raid1 on a server at work sometime soon though...