Xen Server - Hot Backup - Template Version

Hi everyone! Here's a short guide on making a hot backup of Xen Server virtual machines.

The requirements are:

• A Xen Server to back up
• A Nas or a machine with an NFS share

First of all, here's the procedure in a nutshell:

1. You select the virtual machines you want to back up
2. A snapshot is created for each virtual machine
3. From each snapshot a template is created, which will be saved on the NFS share
4. At the end of the procedure the snapshot used to create the template is destroyed
5. Done!

So let's start from step 1: you need to log into the Xen server (ssh) and run the command to see the list of available virtual machines

xe vm-list is-control-domain=false is-a-snapshot=false | grep name-label

You'll get a list like this:

name-label ( RW): Macchina1 name-label ( RW): Macchina2

Assuming you've already connected an NFS share to Xen Server, you should have a situation like this:

Where NAS will be our NFS share. Let's look in the share settings for the id Xen assigned to it

So let's grab the UUID.

The next step is to create a folder on the server that will hold the backup scripts, for example /SCRIPT_HOT_BACKUP/, where we'll put two files:

• name_macchine.txt
• backup.sh

In name_macchine.txt we'll put, one per line, the names of the machines we picked earlier for the backup, in our case

Macchina1 
Macchina2

And we'll write the following script:

#!/bin/bash

SRUID=90097326-80d0-4a1d-b42e-f97743987712

for fn in `cat /SCRIPT_HOT_BACKUP/name_macchine.txt`; do

echo $fn
DATE=`date +"%Y-%m-%d %H:%M:%S"`
SNAPUID=`xe vm-snapshot vm="$fn" new-name-label="$DATE backup $fn"`
xe snapshot-copy new-name-label="$DATE backup $fn" new-name-description="backup di $fn di $DATE" uuid=$SNAPUID sr-uuid=$SRUID
xe snapshot-uninstall force=true snapshot-uuid=$SNAPUID

echo "FINE $fn"

done

As you can see there are a few variables; the only important one to set is SRUID, which will hold the id of the NFS share chosen earlier.

This script will go through every machine name in the name_macchine.txt file and take a snapshot, save the snapshot as a template, and destroy the snapshot.

Once the backup is complete, you'll see the templates in Xen Center! (the GUI management client)

From the command line you'll get output like this:

Macchina1
f3b53574-fe45-f831-665e-ed7d8e59cf24
The following items are about to be destroyed
VM : b190bd5b-ca78-506c-571d-a6471eda7d04 (2016-04-15 21:38:42 backup Macchina1)
VDI: a3fc1deb-4f73-4d6b-98e9-206a3441c2b0 (New virtual disk (14))
All objects destroyed
FINE Macchina1

And that wraps up this little guide to zero-cost hot backups!

🙂