Prior to making any changes to your computer’s drive you need to establish a baseline backup of the entire drive in case you need to restore Windows 10 to its current state (containing all your data files and applications) for whatever reason after installing Windows 10 or you are no longer able to boot to Windows.
The screenshots below shows a typical 1TB drive with 3 partitions when using the Disk Management utility.
The image backups you will create over time, will eliminate the need to use the recovery partition to reinstall Windows 10, and preserves your Apps and data files. Think of these backups as your safety net should you have problems with a particular Windows Update or software application update.
My personal style of where and how to store the Image Backup file includes the use of an external USB drive and a destination folder name (created prior to launching the image backup software). The folder name should have some meaning (Example: Windows10_Initial_Baseline_Backup). Inside this folder I also create a small Notepad Readme.txt file that includes notes about why and when the backup was created.
The time to complete the backup is dependent on the image compression level, amount of data / used drive space your Windows 10 partition contains and to some extent the size of your recovery partition. You can choose Medium or High compression (these option vary depending on what vendor’s Image Backup software you are using) as it provides a good balance between the size of the image backup file on the USB drive and the time to complete the backup. Higher compression levels usually do not save all that much space and can add significant time to the backup completion time.
After your baseline backup has completed, the next step is to shrink the existing Windows 10 (C:) partition to make room for an additional partition to be used when installing Windows 7 or 8.1.
Note: Since I’m using Acronis True Image I suggest you take some time to review and understand the backup “Options” settings. For instance you do not want a scheduled backup as it could overwrite your original backup.
How to dual boot Windows 10 and Windows 7 ----->>> Understanding Disk Drive Partitions and what needs to be backed up ----->>> Image Backup Strategy ----->>> Initial Baseline Image Backup ----->>> How to create space for a Windows 7 partition on your disk drive ----->>> Installing Windows 7 ----->>> Final Image Backup ----->>> How to access the GUI (Graphical Boot Menu) ----->>> Chkdsk always runs on my dual boot computer ----->>>