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[Xen-users] Cannot open root device

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] Cannot open root device
From: Hsing-Foo Wang <hsing-foo.wang@xxxxxxxxxxxxxxxx>
Date: Sun, 05 Jun 2005 08:37:44 +0200
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Hi all,

I am having trouble booting the ttylinux-xen guest os. I followed the example in the manual and exchanged the values to match my system.
I also searched/read this mailing archive.

This is the start command:
'xm create -c ttyvm' where ttyvm is the config file

It starts booting and then halts with the error:
Root-NFS: No NFS server available, giving up.
VFS: Unable to mount root fs via NFS, trying floppy.
VFS: Cannot open root device "md1" or unknown-block(2,0)
Please append a correct "root=" boot option
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)

My hd is a scsi HD known as md1 to the Xen host, output of 'df':
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/md1              70215680   2195812  64453044   4% /
/dev/md0                 77649     36372     37268  50% /boot
none                    251196         0    251196   0% /dev/shm

My host is a Centos 3.4 server

What did I miss please, any guidance much is appreciated for I tried many times myself but failing.



Below is the config file:
[root@sun xen]# cat ttyvm
#  -*- mode: python; -*-
# Python configuration setup for 'xm create'.
# This script sets the parameters used when a domain is created using 'xm create'.
# You use a separate script for each domain you want to create, or
# you can set the parameters for the domain on the xm command line.

# Kernel image file.
kernel = "/boot/vmlinuz-2.6-xenU"

# Optional ramdisk.
#ramdisk = "/initrd.gz"

# The domain build function. Default is 'linux'.

# Initial memory allocation (in megabytes) for the new domain.
memory = 64

# A name for your domain. All domains must have different names.
name = "ExampleDomain"

# Which CPU to start domain on?
#cpu = -1   # leave to Xen to pick

# Define network interfaces.

# Number of network interfaces. Default is 1.

# Optionally define mac and/or bridge for the network interfaces.
# Random MACs are assigned if not given.
vif = [ 'mac=aa:00:00:00:00:11, bridge=xen-br0' ]

# Define the disk devices you want the domain to have access to, and
# what you want them accessible as.
# Each disk entry is of the form phy:UNAME,DEV,MODE
# where UNAME is the device, DEV is the device name the domain will see,
# and MODE is r for read-only, w for read-write.

#disk = [ 'file:/etc/xen/ttyfs,md1,w' ]
disk = [ 'phy:/dev/loop0,md1,w' ]
# Set the kernel command line for the new domain.
# You only need to define the IP parameters and hostname if the domain's
# IP config doesn't, e.g. in ifcfg-eth0 or via DHCP.
# You can use 'extra' to set the runlevel and custom environment
# variables used by custom rc scripts (e.g. VMID=, usr= ).

# Set if you want dhcp to allocate the IP address.
# Set netmask.
# Set default gateway.
# Set the hostname.
#hostname= "vm%d" % vmid

# Set root device.
root = "/dev/md1 ro"

# Root device for nfs.
#root = "/dev/nfs"
# The nfs server.
#nfs_server = ''
# Root directory on the nfs server.
#nfs_root   = '/full/path/to/root/directory'

# Sets runlevel 4.
extra = "4"

# Set according to whether you want the domain restarted when it exits.
# The default is 'onreboot', which restarts the domain when it shuts down
# with exit code reboot.
# Other values are 'always', and 'never'.

#restart = 'onreboot'


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