The persistent state will contain persistent data from objects in the hierarchy rooted at root, or all persistent data if that argument is NIL.
To use this command, no image is allowed to have a writable file already.
If the directory exists, it must contain a saved persistent state previously created by this command, whose objects match the configuration under root, and this state will be loaded and used as writable state. Otherwise a new state will be created.
If -new is specified and the directory dir exists, an error will be raised.
If a new state is created, a description can be added to the persistent state, using the comment argument. The comment is saved in the info file in the persistent state directory.