My recommendation would be to leave the system Partition alone and not mess with it as suggested by some comments saying take it off-line etc
You can read more here
http://www.howtogeek.com/192772/what-is-the-system-reserved-partition-and-can-you-delete-it/
How to backup complete computer
- Open the Control Panel
- Click on the Backup and Restore icon.
- Click on the Create a system image link
- If prompted by UAC, click on Yes.
- Select the location to where you would like to save the backup image at, and click on the Next button. NOTE: See the Warning box at the top of the tutorial. Only the Windows 7 Professional, Ultimate, and Enterprise editions can backup to a network location.
- If available, check any additional hard drives or partitions (ex: Vista) that you would like to include in the backup image with the Windows 7 (System and C: ) partition or hard drive, and click on the Next button.
- Click on the Start backup button.