[Reference:https://cloud.google.com/compute/docs/instances/create-start-instance, , Preparing your instance for an image, You can create an image from a disk even while it is attached to a running VM instance. However, your image will be more reliable if you put the instance in a state that is easier for the image to capture. Use one of the following processes to prepare your boot disk for the image:, , Stop the instance so that it can shut down and stop writing any data to the persistent disk., , If you can't stop your instance before you create the image, minimize the amount of writes to the disk and sync your file system., , Pause apps or operating system processes that write data to that persistent disk., Run an app flush to disk if necessary. For example, MySQL has a FLUSH statement. Other apps might have similar processes., Stop your apps from writing to your persistent disk., Run sudo sync., After you prepare the instance, create the image., , https://cloud.google.com/compute/docs/images/create-delete-deprecate-private-images#prepare_instance_for_image, , , ]