Software Raid's

Building a RAID1 (boot) / RAID5 (root) with ASUS P5GDC-V Deluxe
For the fast and furious:

tools:

• mdadm
• jfsutils

Most important steps for /dev/md0

1. Install Lilo 22.6
2. mknod /dev/md0 b 9 0
3. mdadm -Cv /dev/md0 -l1 -n4 -c128 missing /dev/sdb1 /dev/sdc1 /dev/sdd1
4. mkfs.jfs /dev/md0
5. umount /boot
6. mdadm -a /dev/md0 /dev/sda1 -> (4 disks=[UUUU], only possible if /boot not mounted)
7. mkdir /mnt/newroot
8. mknod /dev/md1 b 9 1
9. mount /dev/md1 /mnt/newroot (do not yet hot-add the 4th disk!)
10. mkdir /mnt/newroot/boot
11. mount /dev/md0 /mnt/newroot/boot
12. find . -xdev | cpio -pm /mnt/newroot (do not use: cp -ax / /mnt/newroot!!)
13. fdisk /dev/sda and make /dev/sda1 and /dev/sda3 "fd"
14. mount -o bind /dev /mnt/newroot/dev/
15. mount -o bind /proc /mnt/newroot/proc/
16. chroot /mnt/newroot /bin/bash/
17. Edit lilo.conf so boot = /dev/md0
18. Lilo -x mbr (Thanks John!!)
19. Edit /etc/fstab
20. The End: Do not forget to 'fd' /dev/sda1 and /dev/sda3
21. If you can not mount /dev/md0 redo mkfs.jfs.
22. Do not forget: To mdadm -a you must boot on md1.
23. And: Do not forget to create the initial console when you are chrooted in /mnt/newroot:

To see which devices nodes are present before the /dev filesystem is mounted, run the following commands:

1. mkdir test
2. mount --bind / test
3. cd test/dev
4. ls

The devices needed for a successful boot are /dev/null and /dev/console. If they didn't show up in the previous test, you have to create them manually. Issue the following commands in the test/dev/ directory:

1. mknod -m 660 console c 5 1
2. mknod -m 660 null c 1 3

When you're finished, don't forget to unmount the test/ directory:

1. cd ../..
2. umount test
3. rmdir test

• Gentoo udev Guide
• Software Raid Howto
• Intel Server Configurator

Speed Settings for Syncing

• /proc/sys/dev/raid/speed_limit_min
• echo 50000 >/proc/sys/dev/raid/speed_limit_min

When having Lilo problems

1. boot from CD
2. mknod /dev/md0 b 9 0
3. mknod /dev/md1 b 9 1
4. mdadm --assemble --run /dev/md0 /dev/hda1
5. mdadm -a /dev/md0 /dev/hdc1
6. mount /dev/md1 /mnt/gentoo
7. mount /dev/md0 /mnt/gentoo/boot
8. mount -o bind /dev /mnt/gentoo/dev
9. mount -o bind /proc /mnt/gentoo/proc
10. lilo -x mbr

Growing a Software Raid1

1. mdadm --grow /dev/md1 --size=max - also see http://www.silfreed.net/content/argo-hard-drive-upgrade-growing-raid1-array
2. Resizing with JFS: # mount -o remount,resize /mount/point - also see http://www.linux.com/articles/32002