Windows Backup weird warnings

Question

This is my setup. 3 x Windows 2016 irons in a HyperV Cluster with MSA storage, hosting around 30 2016 servers for various needs.
Every night each iron selects 1 VM folder and runs a windows backup to a share, the next night it takes another VM
The backup seem to be running fine, depending on the size of VM it takes 60 mins up to 120 mins
Each Folders holds 1 VM including all disks and configuration.

The weird part is that pretty much every jobs ends with a huge list of warnings that some files/folders could not be backed-up, they are skipped.
But all those folders listed was not even part of the backup-job, its pretty much all siblings folders holding other VM
I remember clearly that this was not the case when the cluster was new built and I configured the backup routine.
From start I let the 3 iron pick all VM, not considering which iron currently holding it, but running only one iron with backup at the time.
Now I changed the routine so each iron only backing up its own VM, still only one iron at the time is running backup during the course of the night.

The errors listed in event viewer is several 16389 and it is the VSS Writer having some issues

Answer 1

Hi KjellLiljegren,

According to your description, my suggestions are as follows, I hope to help you:
(1) According to your description, the reason for the above may be that the Windows server backup timed out during the creation of the shadow copy, so such an error will appear.
(2) Open the registry and navigate to the following directory:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\SPP
Create a new registry value of type DWORD named "CreateTimeout" in this directory, and change the value to 12000000 in decimal, which is 20 minutes.

Best Regards,
Xu Gu