How to Backup Running Virtual Machine in XenServer

For many years, I’ve been immersed in the world of Citrix XenServer, managing a fleet of XenServers via XenCenter on a dedicated Windows machine. Traditionally, our approach to VM backup has been a manual process, always necessitating a shutdown of the VM. This practice has understandably led to some frustration among VM owners due to the extended downtime. However, a recent search revealed a more efficient method that allows for backing up VMs without the need to shut them down, thereby eliminating downtime.

In this tutorial, we’re going to guide you through the process of backing up active VMs step by step. Additionally, we’ll introduce you to a shell script that automates the backup of all VMs or specific ones of your choice. This script can be easily integrated into a crontab to schedule regular backups, making the process seamless and efficient.

Method 1: Manual Backup of Running VM

For those who prefer the command line over using XenCenter, especially Linux enthusiasts, here are the steps to manage your VM backups using terminal commands.

1.1. Identifying VM UUIDs

To begin, locate the UUIDs of all your VMs, which are essential for the following steps. Execute the command below to list all VMs, noting their UUIDs and other details:

xe vm-list is-control-domain=false is-a-snapshot=false

Example output might look like this:

uuid ( RO)           : 8ac95696-94f3-83c1-bc89-8bb2603f832b
     name-label ( RW): test-vm
    power-state ( RO): running

From the output, you can see the UUID for test-vm is 8ac95696-94f3-83c1-bc89-8bb2603f832b, though yours will vary.

1.2. Creating a VM Snapshot

Next, create a snapshot of the VM using its UUID from the previous step. Ensure the UUID is accurate:

xe vm-snapshot uuid=8ac95696-94f3-83c1-bc89-8bb2603f832b new-name-label=testvmsnapshot

This command will return a snapshot UUID. Use this new UUID to set the snapshot as a non-template VM, preparing it for export:

xe template-param-set is-a-template=false ha-always-run=false uuid=b15c0531-88a5-98a4-e484-01bc89131561

1.3. Exporting Snapshot to File

With the snapshot prepared, export it to an .xva file, which can be restored later via command line or XenCenter:

xe vm-export vm=b15c0531-88a5-98a4-e484-01bc89131561 filename=vm-backup.xva

1.4. Deleting the Snapshot

After backing up the VM, you can safely remove the snapshot from the XenServer:

xe vm-uninstall uuid=b15c0531-88a5-98a4-e484-01bc89131561 force=true

Method 2: Using Script for Backup Running VMs

To automate backups for all running VMs on XenServer, consider using a shell script. This approach involves mounting a remote filesystem shared via NFS. While the following script has been effective in my experience, its performance may vary for you. Proceed with caution and understand the risks involved.

#!/bin/bash

# Script for backing up running Virtual Machines in XenServer
# Written by: Mr. Rahul Kumar
# Creation date: Jun 14, 2014
# Last updated: Mar 14, 2024
# Version: 1.3
# More information at: https://tecadmin.net/backup-running-virtual-machine-in-xenserver/

DATE=$(date +%d%b%Y)
XS_HOSTNAME=$(hostname)
UUIDFILE="/tmp/xen-uuids.txt"
NFS_SERVER_IP="192.168.10.100"
MOUNTPOINT="/xenmnt"
FILE_LOCATION_ON_NFS="/backup/citrix/vms"

# Create mount point
mkdir -p "${MOUNTPOINT}"

# Mounting remote NFS share backup drive
if [ ! -d "${MOUNTPOINT}" ]; then
  echo "No mount point found, kindly check"
  exit 1
fi

mount -F nfs "${NFS_SERVER_IP}:${FILE_LOCATION_ON_NFS}" "${MOUNTPOINT}"

BACKUPPATH="${MOUNTPOINT}/${XS_HOSTNAME}/${DATE}"
mkdir -p "${BACKUPPATH}"
if [ ! -d "${BACKUPPATH}" ]; then
  echo "No backup directory found"
  exit 1
fi

# Fetching list UUIDs of all VMs running on XenServer
xe vm-list is-control-domain=false is-a-snapshot=false | grep uuid | cut -d":" -f2 | tr -d ' ' > "${UUIDFILE}"

if [ ! -f "${UUIDFILE}" ]; then
  echo "No UUID list file found"
  exit 1
fi

while IFS= read -r VMUUID; do
  VMNAME=$(xe vm-list uuid="$VMUUID" | grep "name-label" | cut -d":" -f2 | sed 's/^ *//g')
  SNAPUUID=$(xe vm-snapshot uuid="$VMUUID" new-name-label="SNAPSHOT-$VMUUID-$DATE")

  xe template-param-set is-a-template=false ha-always-run=false uuid="${SNAPUUID}"
  xe vm-export vm="${SNAPUUID}" filename="${BACKUPPATH}/${VMNAME}-${DATE}.xva"
  xe vm-uninstall uuid="${SNAPUUID}" force=true

done 

Download this script directly from Github.com

• https://github.com/tecrahul/xenvmbackup/blob/master/xenvmbackup.sh

Conclusion

In conclusion, backing up virtual machines without shutting them down is not only possible but also efficient and practical. This guide and the provided script make it easy to regularly backup your VMs, reducing downtime and keeping your data safe. With these tools, you can automate the backup process, ensuring your VMs are always protected with minimal disruption. This method marks a significant improvement in managing VM backups, offering a solution that is both user-friendly and highly effective.