My first attempt at upgrading to Windows 10 & performing a clean install the first time went very poorly. Fortunately for me I chose one of my least important netbooks to experiment with Windows 10.
(Most of my experience & habits were developed over lots of clean installs of XP & fewer factory resets of Windows 7. These always fixed any problems that had developed over time. After getting tired of all the extra work that I constantly had to move,
backup transfer etc. I developed the philosophy of creating another partition on my hard drive where I store all of my Documents - I used EaseUS Partition Master, Free. I personally made this documents partition about 75% of the total capacity of the hard
drive while leaving the first 25% for the OS - 80GB max. Then I move all my documents to the Documents partition. All XP clean installs & my Factory Resets of Windows 7 only affect the partition that holds the OS thus keeping the documents on the other partition
always kept them safe from deletion & saved tons of time once the new install / reset was complete. The final step I'd developed on previous windows versions is after the Clean install / factory reset is complete is to locate the Documents folder in the default
OS folder on the OS partition & through the Properties of the folder Location tab move the folders to the Documents partition. Since before wiping out the OS partition I had already moved all the documents to the Documents partition I can simply tell the
Windows to use my old folder for all the Documents. In XP I only had to do this with one folder. In Windows 7 they started using multiple folders, thus it is a bit more laborious, but the same results could always be achieved if I did the same process to
each of the Download, Contacts, Music, Video, etc. folders immediately after the fresh install / reset was complete. If I moved the documents immediately this redirection on the new OS was nearly instant since the fresh install document folders were empty.
If I waited and created a bunch of new files before moving to my documents to the Documents partition I'd have to wait for all the new files to be physically moved. Once I'd told window to use the existing documents folder on the Documents partition I had
access to all my pre Clean Install / Factory Reset documents.)
I said all the above to say as my personal background and for a basis for some of my comments later regarding my attempt at a clean install of Windows 10 the first time. What happened when I chose not to keep all the old applications & folders etc. on my
first attempt to install Windows 10 was that the Install process not only wiped my OS partition, but it wiped my Factory Reset & boot partition of my original Windows 7 making it impossible for me to go back to Windows 7. The other thing I found is Windows
10 would not accept my Windows 7 drivers from the netbook manufacturer on their website. The manufacturer only offered Windows 7 drivers so I could not install Drivers to be able to turn on WiFi radio etc. from buttons, etc. This was unacceptable. It was
at that point I thought there was no need to panic, I could do a factory reset. That was when I learned the boot partition had been altered & no longer gave me the F2, F8, F10, etc. option to go into Boot Recovery & Install Windows 7 via the Factory Recovery.
So whether it wiped the Recovery partition or not was irrelevant since I no longer had access to to it in while the computer was booting up. I was fortunate that I had 3 identical netbooks & through trial & error was able to copy my Factory Recovery & Boot
partitions from one of my other identical netbooks over to the Windows 10 / messed up netbook & then Factory Reset it to Windows 7 so that all the hardware would have drivers. After that I was able to successfully Upgrade to Windows 10 by choosing to keep
all my applications & folders the 2nd time around. If I personally did not have access to an identical windows 7 netbook, the Clean Install to my netbook would have made my netbook nearly useless, since things like WiFi are necessary for daily use.
This is shared as, for whatever it is worth information about my experiences on some of the topics being discussed on this thread lately.
Up until Windows 10 I have always highly recommend my method of moving Documents to a 2nd partition for the fastest access to all the info after a clean install or Factory Reset. However I can't say from experience whether Windows 10 will allow you to keep
them safe on a 2nd partition safely or not. I never dreamed the Clean Install would touch my Factory Recovery & Boot partition, but it did on my machine so I can't say yet from personal experience that it worked for me even once. In my experience which shared
above, I never got that the machine hardware working properly after the Windows 10 Clean Install so I never event checked the Documents Partition since, like I said, I had no critical Data to even be concerned to look for them. Until I buy a new machine I
won't be brave enough to even attempt another Clean Install again. I will wait until I have a machine with a Windows 10 Factory Recovery partition.
For me the Clean Install was not a good option & I was fortunate I had the option to experiment with the new OS on a machine that contained no critical Document data as well as an identical machine that save my butt. After over 24+ hrs. of my personal labor
I saved it. Who knows if I could have even paid a computer shop to solve this for me without the identical netbook to the original Windows 7 Factory Recovery & boot files.
Good luck to all others debating these topics. The Cloud backup method mentioned by someone on this thread maybe the safest, but it is likely the very slowest method to be able to replace valuable files should they ever be lost in a Clean Install if a 2nd
partition can't keep them safe from the newer Windows 10 Clean Install procedures.