1. A method implemented at least in part by a computer, the method comprising: receiving an indication of a file system object of a local file system of a client, the client structured to synchronize the local file system with a remote storage system; evaluating one or more factors to determine an action to take with respect to the file system object, the action selected from actions that include: to hydrate, to dehydrate, and to do nothing with respect to the file system object; and if the action is to dehydrate the file system object, performing dehydration actions, the dehydration actions comprising: creating or maintaining a placeholder to represent the file system object, the placeholder being stored on the local file system, the local file system structured to obtain metadata of the file system object from the placeholder, the metadata sufficient to allow the client, while offline with respect to the remote storage system, to obtain namespace information about the file system object from the placeholder, the placeholder including data that identifies the remote storage system from which content of the file is obtainable, updating the placeholder to indicate that the file system object is dehydrated, and purging the content of the file system object from the local file system while maintaining the metadata of the file system object in the placeholder.