Assuming a full backup of the NODE ganeti node exists on backup.tld, here are the steps to resurect it on a new disk:

• boot on a live CD with the same architecture as NODE
• fdisk /dev/sda
• create sda1 root 20GB, sda2 swap XGB (amount of RAM), sda3 LVM
• reboot so that it is taken into account (in case it is ignored because the disk is considered active, fdisk will tell)
• mke2fs -t ext4 /dev/sda1 ; tune2fs -i 300 -c 300 -m 0 /dev/sda1
• mount /dev/sda1 /mnt
• ssh -A root@…
• rsync -avHz --numeric-ids backup.tld:/NODE/ /mnt/
• vi /mnt/etc/network/interface and update eth0 according to what ifconfig eth0 says
• chroot /mnt
• grub-install /dev/sda
• mkdir /sys /proc
• mount -t proc none /proc
• vgreduce --removemissing all
• vgremove all
• rm -fr /dev/all
• pvcreate /dev/sda3 (assuming it is LVM type)
• vgcreate all /dev/sda3
• pvremove /dev/XXX (this is assuming the disk layout on the new machine is different from the one on the previous machine)
• vi /mnt/etc/fstab # fix whatever needs to be
• reboot on root with a network kernel http://guides.ovh.com/KernelNetboot
• update-grub
• on OVH manager switch back to hd boot
• reboot
• update /etc/hosts with the latest from another active host of the cluster
• update all other hosts /etc/hosts with the IP of the newly resurected host
• edit /etc/shorewall/params.local and set MAIN to z2-X.pokersource.info and FAILOVER to z2-X1.pokersource.info
• cd /etc/dhcp3 ; hg pull ; hg update ; /etc/init.d/dhcp3-server restart