Method and apparatus for shared persistent virtual storage on existing operating systems

The preferred embodiment present invention provides a shared persistent virtual storage system and method for creating and managing a large logical virtual address space, called a shared address space (SAS), on existing systems. The shared persistent virtual storage system provides an interface layer between client processes using the SAS addresses and the underlying system. By providing the ability to use a large shared address space, the preferred embodiment allows the creation and sharing of persistent objects using single level store semantics. The preferred embodiment does this by mapping the shared address space to backing store as needed, and by implicitly moving portions of data, called pages, between backing storage and main memory as needed by client process. The preferred embodiment then provides a mechanism for translating shared address space addresses into a native address of the data in the page cache and providing that address to the application. Thus, the preferred embodiment provides the ability to store data using proven single level storage techniques in commodity systems that use smaller native addressing. This data can then be easily shared between client processes using the shared address space addresses.