Hello,
As per the description, you are experiencing issue with error message: “Backup failed as shadow copy on source volume got deleted. This might cause by high write activity on the volume. Please retry the backup. If the issue persists consider increasing shadow copy storage using 'VSSADMIN Resize Shadow Storage' command. (0x80780169)” on the system.
I certainly understand your concern and appreciate all your efforts in trying to fix the issue.
I would suggest you to refer to the suggestions provided in the following Microsoft Community link given below and check if that helps.
Also, I would suggest you to refer to the article given below and check if that helps.
What is a system image?
http://windows.microsoft.com/en-IN/windows7/What-is-a-system-image
I hope this information is helpful.
Please do let us know if you need any further assistance, we will be glad to assist you.
Thank you.