Free tool to backup VMs on Xenserver Host

Few months back, I came across a fantastic software to backup Xenserver virtual machines without any downtime. It is Xackup from Fungusware. I am using this tool in my production environment. It works fine without any issues.
The features are

1. It can Backup, Restore or Migrate VMs from Xenserver Hosts.
2. It takes a snapshot of the VM and then exports the VM in compressed format to the storage. After the backup process, it automatically deletes the snapshot file from the server.
3. It takes the differential backup. So it saves space on storage end.
4. Email alerts let us know the status and the whole background process of the backup and restoration.
5. It can migrate or (or clone) a Virtual machine between XenServers without having to use an intermediary storage medium.
6. You can schedule your Virtual Machines to be backed up on a given schedule
7. Xackup attempts to keep you informed of its progress at all times.

It uses Simple mechanism as follows:


It don’t use any propriety storage formats, backups are stored as compressed archives and use the standard XenServer methods to do all the work. That means if something should happen to go wrong, we always have the ability to manually intervene and make sure your VMs are always safe.