To add visibility posting an answer.
As per this article, Windows instances using image v20160810 or newer are pre-configured to work with VSS.
Additionally, on this discussion, Amruta has provided some guidelines to confirm GCE-VSS agent is running and instructions on how to access the logs:
“If the images is earlier than the one mentioned below or if there is an issue with the VSS Writers, the snapshot will fail. You will see and error code returned by the the API.
You can check the status of VSS Requester, VSS Provider and Vanadium while taking a VSS enabled snapshots using the following steps :
Go to Windows Service Manager (run services.msc under an elevated command line windows), make sure Google VSS Agent is running. If the service state is stopped, VSS snapshot will always fail.
The additional status can be obtained by checking the status of the Google Vss Requestor and Provider will require access to the Windows Event Log inside of the guest. The four event logs are named: 'GCE-VSS-Agent/Debug', 'GCE-VSS-Agent/Operational', 'GCE-VSS-Provider/Debug', 'GCE-VSS-Provider/Operational'
Example using Powershell: wevtutil query-events , E.g. wevtutil query-events GCE-VSS-Agent/Debug
By default, only operation Log is enabled, to get more diag info, we might need to turn more logging. Example: wevtutil sl GCE-VSS-Agent/Debug /e /q
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