Method and system for transparently extending non-volatile storage

Abstract

Briefly, the present invention provides a system and method for transparently extending the non-volatile storage on a computer system via links from one drive to one or more other drives. When the user adds a new disk drive, it is formatted but not mounted where the user can see it. The data of selected files is automatically migrated from the original drive to the new, supplemental drive, or directly created thereon, and a link is placed on the original volume to indicate to the system that the data is really elsewhere. In one implementation, this is accomplished via an NTFS reparse point on an NTFS link that is made a sparse file, thereby reclaiming the disk space on the original drive. A driver in the NTFS filter stack or the like in conjunction with the file system handles directing reads and writes to the new location, and also handles other operations including totaling the free space of each drive in response to a free space request. The driver may also enforce file operation rules, that may depend on whether the supplemental drive and/or supplemental file system is present or removed, and so forth. In this manner, the size of the original drive increases from a user's perspective, while providing a unified view of namespace, with file names present even when the supplemental drive is removed.