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Migrating a 32bit server to a 64bit server as a Xen image

25 Feb, 2008

I've got a 32bit intel Mac Mini server running Ubuntu Dapper Drake and I wanted to package it up as a Xen image to run on an AMD 64 server running Debian. Here's what I did.

First create the Xen image on the 64bit server:

sudo mkdir /var/xen
sudo xen-create-image --debootstrap --dir=/var/xen --size=60Gb --memory=512Mb --fs=ext3 --dist=etch --hostname=vm2 --ip 78.47.146.253 --netmask 255.255.255.248 --initrd=/boot/initrd.img-2.6.18-4-xen-amd64 --kernel=/boot/vmlinuz-2.6.18-4-xen-amd64 --mirror=http://ftp.freenet.de/debian/ --swap=1024Mb

Then mount it:

sudo mkdir /mount/vm2
sudo mount -t ext3 -o loop /var/xen/domains/vm2/disk.img /mount/vm2

Then sync the filesystems:

cd /mount/vm2/
sudo rsync -aHxvzgop  --progress --delete --numeric-ids root@pauli.3aims.com:/ .

Now shutdown the old server because any changes will be lost.

Create a new fstab for the copy on the 64bit server after backing up the old one:

sudo cp -p /mount/vm2/etc/fstab /mount/vm2/etc/fstab.bak

Make the new one like this:

/dev/sda1     /     ext3     errors=remount-ro   0     1
proc          /proc proc     rw,nodev,nosuid,noexec              0     0
/dev/sda2     none  swap     sw                    0     0

Unmount the disk and boot the image:

# You can't unmount a directory you are still in so we move out.
cd ..
sudo umount /mount/vm2
# You might want to skip this, it takes ages.
sudo cp /var/xen/domains/vm2/disk.img /var/xen/domains/vm2/disk.img.bak
sudo xm create -c /etc/xen/vm2.cfg

Check the server is up and can ping and be pinged then change the DNS settings to point all the services to the new server.

You might need the lib64 modules:

sudo mount -t ext3 -o loop /var/xen/domains/vm2/disk.img /mount/vm2
sudo cp -r /lib/modules/2.6.18-4-xen-amd64 /mount/vm2/lib/modules/
sudo ln -s /mount/vm2/lib /mount/vm2/lib64
sudo umount /mount/vm2
sudo xm create -c /etc/xen/vm2.cfg

Also need to mess with any files containing the wrong IP. Some of these commands might be handy:

sudo mount -t ext3 -o loop /var/xen/domains/vm2/disk.img /mount/vm2
sudo cp -pr /mount/vm2/etc /mount/vm2/etc.bak
cd /mount/vm2/etc
sudo grep -rl "212.69.38.27" . 2> /dev/null
sudo perl -pi -e 's/212.69.38.27/78.47.146.253/g' /apache2/vhosts/*
sudo grep -rl "212.69.38.27" . 2> /dev/null
cd /
sudo umount /mount/vm2
sudo xm create -c /etc/xen/vm2.cfg

Finally you'll need to update your networking configuration, here's how mine look, /etc/network/interfaces:

auto lo
iface lo inet loopback

# The primary network interface
auto eth0
iface eth0 inet static
 address 78.47.146.253
 network 78.47.146.248
 netmask 255.255.255.248
 up route add 78.46.35.5 dev eth0
 up route add default gw 78.46.35.5
 down route del default gw 78.46.35.5
 down route del 78.46.35.5 dev eth0

and /etc/resolve.conf:

### Hetzner Online AG installimage
# nameserver config
nameserver 213.133.99.99
nameserver 213.133.100.100
nameserver 213.133.98.98

I run ISPConfig too so I also need to update its database so changes it makes for bind are correct:

mysql> update dns_a set ip_adresse='78.47.146.253' where ip_adresse='212.69.38.27';
mysql> update dns_isp_dns set dns_soa_ip= '78.47.146.253' where dns_soa_ip='212.69.38.27';