tested on XenServer 5.5 and works flawlessly. I did most of the work by my self though… those sed and awk seemed to complex to type my hand… :p

For future readers: Be careful with the mount and then the copying over of the sda filesystem to the software raid device if you’ve already added the server to an attached storage repository. Without providing the proper rsync exclude it will attempt to copy over the contents of your storage repository and quickly fill your disk. I did this mindlessly once and decided I would just delete the extra files off the disk after unmounting the shared storage. Unfortunately, i forgot to unmount the shared storage. yeah, that sucked.

Only thing that worries me a bit is the remark about “boot loader code” written to one disk.

I’m been trying to get this to work in a 5.5 server and first reboot works fine. It seems as soon as I add the sda1 partition to md0 things fall apart on boot? It just keeps rebooting. I used the troubleshooting boot command above and I get a kernel panic and a message about I/O resource already in use.

Any ideas?

I used the text file mentioned above:
http://core.bofh.lv/XenServer-on-RAID.txt
another hard drive with a fresh install of xenserver
and a centos live CD

The problem was that I blindly copied and pasted this entire setup above hoping for the best. I really don’t know why it booted in the first place, and I frankly don’t care enough to figure it out.

Here is what I did.

made a fresh install of xenserver on another hard drive
booted onto the centos liveCD with all 3 hard drives installed
started at step 6 of the text instructions, creating a new initrd ramdisk.

I mounted md0 to /mnt/disk/md0. /dev/sdc1 was already mounted to /mnt/disk/sdc1
I used the fresh install to get the source files and replaced the files on the raid array.

And it booted without a hitch.

I followed through all the steps, and the mirror came up, rebuilt and was running clean, yay!

I assumed all was good, so spent a day creating my virtual machines.

But then I rebooted the physical server to move it, and that was the last time it booted. :’(

When you hit escape on the blue boot splash screen, this is what come up:

> map: vt01 => fb0
> could not find filesystem: ‘/dev/root’
> setuproot: moving /dev failed – no such file or directory
> setuproot: error mounting /proc – no such file or directory
> setuproot: error mounting /sys – no such file or directory
> switchroot: mount failed – no such file or directory
> kernel panic – not syncing: attempt to kill init!

So, I tried the troubleshooting step, which gets much further, but then panics anyway. I cant pause the screen, and everything goes by so fast. This is one of the errors that I saw:

Extfs unreadable superblock

BLEH. I guess I will go find a live boot CD of some sort, and see what else I can break.

Thanks for your help, and if you could explain the steps it would be awesome, since I am just learning Linux.

[root@virtual ~]# fdisk -l

Disk /dev/sda: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sda1 * 1 499 4008186 fd Linux raid autodetect
/dev/sda2 500 998 4008217+ 83 Linux
/dev/sda3 999 19457 148271917+ fd Linux raid autodetect

Disk /dev/sdb: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start End Blocks Id System
/dev/sdb1 * 1 499 4008186 fd Linux raid autodetect
/dev/sdb2 500 998 4008217+ 83 Linux
/dev/sdb3 999 19457 148271917+ fd Linux raid autodetect

Disk /dev/md0: 4104 MB, 4104257536 bytes
2 heads, 4 sectors/track, 1002016 cylinders
Units = cylinders of 8 * 512 = 4096 bytes

This doesn’t look like a partition table
Probably you selected the wrong device.

Device Boot Start End Blocks Id System
/dev/md0p1 ? 402920848 433755839 123339962 78 Unknown
Partition 1 does not end on cylinder boundary.
/dev/md0p2 ? 54108890 151069367 387841909+ 10 OPUS
Partition 2 does not end on cylinder boundary.
/dev/md0p3 ? 233695321 473599079 959615034 8b Unknown
Partition 3 does not end on cylinder boundary.
/dev/md0p4 ? 404488193 405528591 4161595+ a OS/2 Boot Manager
Partition 4 does not end on cylinder boundary.

Partition table entries are not in disk order

Disk /dev/md1: 151.8 GB, 151830331392 bytes
2 heads, 4 sectors/track, 37067952 cylinders
Units = cylinders of 8 * 512 = 4096 bytes

Disk /dev/md1 doesn’t contain a valid partition table
[root@virtual ~]#

http://core.bofh.lv/XenServer-on-RAID.txt