At work I am currently doing a trial run with Barracuda’s Backup Appliance. I got it racked and configured (with quite a bit of annoyance since you have to call their support to bond NICs) and kicked off the initial full backup and received the following “Unable to quiesce disk” errors.
Since I was already working with Barracuda’s engineer on the LACP and some upload throttles, I asked his opinion on the matter. Long story short he pretty much told me to investigate VMware and I’ll probably find the issue, and that I did. When I tried to manually take a snapshot selecting the “Quiesce guest file system (Needs VMware Tools installed)” I received the following error:
The guest OS has reported an error during quiescing. The error code was: 5 The error message was: ‘VssSyncStart’ operation failed: IDispatch error #8462 (0x8004230e)
Digging through the VMware forums I found that my issue was with the Volume Shadow Copy Services Support part of VMware Tools. I uninstalled VMware Tools and re-installed, but instead of selecting a complete installation I selected Custom and did not install the Volume Shadow Copy Services Support.
Once that completed installing and I restarted the effected machines, the issue was resolved!