I am running the Create System Image function in Windows 7. However, it works while windows is running, it doesn't ask me to reboot and then start backup in without Windows running! How is it able to do that? How is it able to back up system programs that are in use? I'm afraid to trust this image so I'm doing another one with Clonezilla "just in case".
migrated from stackoverflow.com Jan 21 '13 at 13:51
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Windows has a feature called Volume Shadow Copy that enables it to take backups from running systems.
This feature has been deprecated in Windows 8. It can be found in the Control Panel as Windows 7 File Recovery.
The vast majority of system processes used are loaded into the memory. The source file still exists, and the system image can be created from this.
For the ones that aren't, nothing stops them being read at the same time by two different programs.
I should also imagine there are some nifty tricks built in to windows to allow windows to use a System Admin level account to access things you might not be able to, as a user.
EDIT: The reason other programs might need a reboot is because they run with your privileges, not with Windows own privs. This means they need to set up a scenario in which they have the rights to copy these system files.