I'm going to upgrading my win7 to 10 this weekend. All I've learnt is that the upgrading process is easy and won't do harm to existing data.
I'm wondering what happens to system partition while the upgrading process? Will old files be replaced? or new files will be added? or something else.
All Windows 7 files will be replaced with Windows 10 versions.
While an in place upgrade does preserve your data you would do well to have a full backup of these files. You should always have a backup of all your important files, 2 or more backup copies for files of particular importance. Doing an OS upgrade makes this doubly important. There are too many opportunities for user error and for things to go wrong to be without a backup.
When the upgrade succeeds, that is generally the case. But when it fails, and it DOES, anything can happen to your files and data. And if your Win7 PC is left in an unusable state (as was my HP laptop), you might have to use data recovery apps to get the files and folders off the drive, as the machine does not boot at all.
So, do a backup BEFORE the upgrade -- so you can get stuff back if needed later.
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