Generally windows doesn’t allow to backup system image in USB flash drive. This is because of the size limitation, as the size of the disk images can go up to GB’s. In case if you have a bigger USB drive, then it is worth to back up in it considering its portability.
There is no straight forward way to backup image to USB. The following steps to be performed to achieve the task.
1) Create a directory on your USB drive
2) Right-click the directory and choose “Share with”, “Specific people”- choose yourself from the list of users and click Share and Done
3)In the “Create System Image” menu choose “On a network location”- now enter the URL for your share (\\your-computer\sharename)- enter your username and password and click OK
Reply by CK1968