Have I really backed up my system?

jimox1999

Distinguished
Feb 6, 2016
32
1
18,545
I decided to backup my Windows 10 drive (C:) prior to updating my Asus mobo BIOS - I've never done either of these before - so I bought a 2TB Seagate external drive and plugged it in.
On the new drive was a link to a Microsoft help page/ guide for backing up Windows 10, which I followed choosing to copy both partions ("C" - containing Windows and "F" - games) on my Samsung ssd .
After 15 mins I was getting error messages and requests to restart the process, this went on for the next few hours but then the I got this -
"The backup failed as a shadow copy on the source volume got deleted.This might caused 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).
Not a clue what this means or how to do it.
Anyway I noticed that in the Seagate 2 new files had appeared - "MyKitchenPC" and "Windows Backup" but in properties the 2 files show as "zero kbs/no folders".
Though in "ThisPC" the Seagate had about 119GB used.
After deleting the 2 "zero" files I tried again but used another guide and this time I got a window showing me what was being copied to the Seagate and how much percent had been done, this took an hour to finish and again 2 "zero Kb files/no folders" icons have been created in the Seagate but "ThisPC" now shows 251GB has been used up.
So is there anyway I can be sure I've done a proper copy of my system please?