Xen server - Hot Backup - .xva version

Hi everyone! Here's another version of this guide on making hot backups 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 short:

1. You pick the virtual machines you want to back up
2. A snapshot is created for each virtual machine
3. Each snapshot is exported to an .xva file and saved on the NFS share
4. At the end of the procedure, the snapshot used to create the xva 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 similar to this:

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

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

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

So we grab the UUID.

The next step is to create a folder on the server to 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 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 $fn"` 
xe vm-export vm=$SNAPUID filename="/var/run/sr-mount/$SRUID/$DATE$fn.xva" 
xe snapshot-uninstall force=true snapshot-uuid=$SNAPUID 
echo "FINE $fn" 
done

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

This script goes through every machine name listed in the name_macchine.txt file and takes the snapshot, saves the xva file and destroys the snapshot.

Once the backup is complete, you'll have all the .xva files in the NFS destination picked earlier. On the command line you'll get output similar to this:

Macchina1 Export succeeded 
The following items are about to be destroyed 
VM : cfa16755-187e-bd93-b828-7772db6a35ef (2017-05-25_20_07_27 backup B_K07_FWPD9) 
VDI: 8c8b0d5a-33f3-4dd9-aeba-2375805458fa (New virtual disk (14)) 
All objects destroyed FINE Macchina1

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

🙂