Technical Architecture Solutions, a VMware Authorized Consultant (VAC), released a very interesting free tool for perform virtual machines hot backup on VMware ESX Server 3.0 platform:
Vi3Backup is a wrapper that we?ve written to put around vcb at the console level to make it easier for people to perform full machine snapshots. It?s trying to do some of the things that VMBK did within Vi3.
It?s been designed to be run at Host level rather than VirtualCenter and by default will export all running machines to a directory of your choice. Optionally it will also compress the file, store multiple copies and allow you to set exclusion lists for VMs that you don?t want backed up.
Whilst it?s ready to go as a cron job for scheduled snapshotting it?s also got an interactive mode so that it can be used to quickly enumerate the running machines on an individual host.
Download it at source.