In a recent article found on Redmond Mag, Chris Wolf does it again, this time helping us out with using Microsoft Virtual Server 2005 R2 SP1, VS Writer and Volume Shadow Copy Service (VSS) to backup live, running virtual machines.  He writes: 

In order to take advantage of VS Writer, you have two options:

• Use backup software that supports VS Writer (note that support for shadow copies does not guarantee support for VS Writer).
• Write a script that creates the shadow copy of the virtual machine files and then backs them up.

VS Writer does some great things when it is called. For instance, if the guest OS, such as Windows Server 2003, supports VSS, then VS Writer can talk to VSS inside a VM guest OS to properly prepare its applications for a shadow copy. Guest operating systems that do not support shadow copies, such as Linux guests, will be automatically suspended prior to the shadow copy, and then resumed once the shadow copy completes.

In the past, administrators had to manually suspend and resume all VMs to successfully create a reliable shadow copy. This approach is used in Jeff Trumbull's excellent script. Note that for shadow copy backups of virtual machines to work successfully, they all must have the latest edition of the Virtual Server VM additions installed inside their guest OS. For Linux VMs, please see Ben Armstrong's blog on the subject.

Backup software that supports VS Writer can back up running virtual server VMs by creating a volume shadow copy that contains each of the VMs' open files and then backing up the VM files associated with the shadow copy.

If your backup software does not support VSS and VS Writer, then you can still reliably back up Virtual Server VMs from the physical host using a vbscript.

Read the entire article on RedmondMag, here.  You can also add a comment or just thank Chris Wolf as well.