Good backup solution for Xen virtual machines?

we are looking for a backup solution for our xen servers that meets the following requirements:

1. makes backups while machines are running
2. has easy to use disaster recovery without depending on complex infrastructure in case of a disaster
3. can backup all kinds of linux and windows machines
4. sends some kind of message if something is not working. We dont want to monitor everything manually

We tried Acronis Backup & Recovery 10 virtual edition but it is not compatible with linux vms. Bacula does not seem to have good disaster recovery, as far as we know.

My question: What are good backup solutions for our requirements?

Thanks advance for your answers.

Cheers

Arne

moved to https://serverfault.com/questions/230062/good-backup-solution-for-xen-virtual-machines