Method and apparatus for interfacing with a secondary storage system

A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for processing a request directed to a secondary storage system, the method comprising:

• receiving the request at an interface of the secondary storage system;
• and
• processing the request by transferring data between a location within the secondary storage system to which the request is directed and a target buffer for the request located outside of the secondary storage system;
• wherein if a target buffer is located within a user space of an application, processing the request involves communicating with the target buffer located within the user space without passing through a page cache.

An apparatus that facilitates processing a request directed to a secondary storage system, comprising:

• an interface within the secondary storage system that is configured to receive the request directed to the secondary storage system;
• a request processing mechanism within the secondary storage system that is configured to process the request by transferring data between a location within the secondary storage system to which the request is directed and a target buffer for the request located outside of the secondary storage system;
• and
• a page cache for storing pages of virtual memory, wherein the page cache is configured to make requests on the secondary storage system through the interface;
• wherein the interface is additionally configured to receive a file system request from an application, wherein the file system request specifies that the target buffer is located within a user space of the application wherein if interface receives a request specifying that the target buffer is located within a kernel space of the operating system, the request processing mechanism is configured to process the request by communicating with the target buffer located within the kernel space without passing through the page cache.