The disclosed systems and methods enable an application to start operating and servicing users soon after and during the course of its backup data being restored, no matter how long the restore may take. This is referred to as “instant application recovery” in view of the fact that the application may be put back in service soon after the restore operation begins. Any primary data generated by the application during “instant application recovery” is not only retained, but is efficiently updated into restored data. An enhanced data agent and an associated pseudo-storage-device driver, which execute on the same client computing device as the application, enable the application to operate substantially concurrently with a full restore of backed up data. According to the illustrative embodiment, the pseudo-storage-device driver presents a pseudo-volume to the file system associated with the application, such that the pseudo-volume may be used as a store for primary data during the period of “instant application recovery.”