clone-linux-volume-remotely.md

Clone linux volume remotely using dd and ssh

*Tags: #ubuntu #lvm #dd #ssh *

Description

This document describes process of cloning a linux LVM volume from one machine to another remotely using dd and ssh. The volume is a root system volume.

Tools

We will use the following tools:

  • Ubuntu 18.04
  • LVM2
  • openssh-server
  • dd

In addition we would need:

  • Two USB sticks with live Ubuntu image
  • Ethernet cable

Process

We clone a linux volume from host to a client. In case we clone a system volume, we ould need two live USB drives both for host and client.

In addition, we have a non-LVM UEFI partition, we have sample partition map of the LVM volume group on the host as following.

boot ubuntu-vg 2,00g # mounted to /boot
home ubuntu-vg 1000,0g # mounted to /home
root ubuntu-vg 80,0g # mounted to /
swap ubuntu-vg 8,0g # swap partition

On the client we reproduce exactly the same partition map and perform Ubuntu installation. Firstly, partition disk to have at least two volumes for EFI and the systems. For example, if the disk is /dev/sda you would have /dev/sda1 for EFI and /dev/sda2 for your LVM.

pvcreate /dev/sda2
vgcreate ubuntu-vg /dev/sda2
lvcreate -L2G -n swap ubuntu-vg
lvcreate -L2G -n boot ubuntu-vg
lvcreate -L80G -n root ubuntu-vg
lvcreate -l 100%FREE -n home ubuntu-vg

When performing Ubunt installation, choose /dev/sda1 as your EFI parition, and the swap, boot, root, home with corresponding mount points ant ext4 file system.

Setup SSH

After installing the OS, we can stay on the live USB. Directly connect by ethernet and configure the SSH on the host:

# set password for root
sudo passwd root

# install ssh server
sudo apt update 
sudo apt install openssh-server

# allow ssh for root
nano /etc/ssh/sshd_config
# Uncomment and set PermitRootLogin to yes

Important! If you don’t do this, the OS will not be able to boot anymore. Using blkid we need to get the UUID of the UEFI volume and the root partitions.

Clone volume

Clone with the following command:

ssh root@192.168.0.1 dd if=/dev/ubuntu-vg/root bs=16M | dd of=/dev/ubuntu-vg/root bs=16M status=progress

Restore UUIDs of volumes

Edit /etc/fstab change Boot volume UUID to client’s UEFI volume UUID.

Lastly, restore the UUID of client’s root volume: tune2fs -U $(rootuuid) /dev/ubuntu-vg/root