PTAB

IPR2019-00600

NetApp Inc v. KOM Software Inc

Key Events

Petition

petition

Title: Restricted Write Access for Data Storage
Brief Description: The ’624 patent discloses a method and system for providing restricted access to a data storage medium. The invention uses a "trap layer" (also called a filter layer) logically positioned between the application layer and the file system layer of an operating system to intercept file access requests and enforce access privileges.

Prior Art Relied Upon: Walker (Canadian Patent No. 2,270,651).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner asserted that Walker anticipates every limitation of claims 1-31. The core of this argument rested on the contention that the ’624 patent’s priority chain was broken, making Walker—a patent application filed by the same inventor with a nearly identical specification and figures—qualifying prior art. Walker was alleged to disclose a method of providing access privileges by using a "trap layer" to intercept operations on a logical storage medium. This interception allegedly occurs regardless of user identity and transparently to the user and application, and the trap layer can subsequently allow, modify, or deny the operation, thus meeting all limitations of the independent claims.
- Key Aspects: The strength of this ground relies heavily on the argument that a filing date error by the Patent Owner broke the priority chain, making the Patent Owner's own earlier, near-identical disclosure anticipatory prior art.

Prior Art Relied Upon: Walker (Canadian Patent No. 2,270,651) and Vossen (Patent 6,026,402).
Core Argument for this Ground:
- Prior Art Mapping: This ground was presented as an alternative to Ground 1. To the extent Walker was found not to teach the limitation that interception occurs "transparently to the user and transparently to a computer application," Petitioner argued that Vossen supplied this teaching. Vossen described a "process restriction file system filter" that maintains transparency to applications by manipulating the path name returned to the application.
- Motivation to Combine: A POSITA would combine Walker and Vossen because both references operate in the same field of Windows NT filter drivers and address the common goal of intercepting I/O requests. Vossen's method of achieving transparency was presented as a known technique that a POSITA would have been motivated to apply to Walker’s system to create a more robust, application-neutral driver, which was a known design goal.
- Expectation of Success: A POSITA would have had a reasonable expectation of success in combining the references. Since both documents describe implementing filter drivers in a Windows NT environment, integrating Vossen’s established transparency functionality into Walker’s similar filter driver architecture was argued to be a straightforward and predictable modification.

Prior Art Relied Upon: Nagar (Windows NT File System Internals, A Developer's Guide, 1997).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Nagar, a foundational text on Windows NT, anticipates system claims 12-21. Nagar was asserted to disclose a system for applying access privileges via a "filter driver," which functions as the claimed "trap layer." Specifically, Nagar’s example of a virus-detection filter driver intercepts all I/O requests targeted to a logical volume. The driver then inspects the request and, based on its content (e.g., presence of a virus signature), either permits the write operation ("allowing said attempted operation") or rejects it ("denial means for denying said attempted operation"). This entire process was described as occurring transparently to the I/O Manager above and the file system driver below it.
Additional Grounds: Petitioner asserted an additional obviousness challenge against claims 12-21 based on Nagar, arguing that even if Nagar did not anticipate, its teachings on combining various filter driver functions would render the claims obvious.

"trap layer" (Claims 1, 12, and 22): Petitioner contended this term was central to the invalidity analysis.
- Petitioner proposed the construction: "a Windows NT filter driver logically disposed between the application layer and the file system layer."
- This construction was argued to be supported by the specification and prosecution history and was critical for mapping the claims onto the prior art, especially Nagar, which explicitly details the structure and function of such filter drivers. Petitioner argued against the Patent Owner's proposed functional definition, asserting that the term has a structural meaning in the context of the patent.

Broken Priority Chain: A central contention underlying the Walker-based grounds was that the ’624 patent is not entitled to its claimed priority date prior to January 2, 2002.
- Petitioner argued that the priority chain was broken because an intermediate application (which issued as the ’864 patent) was filed one day after its parent application (the ’175 patent) issued. This allegedly violated the statutory requirement of 35 U.S.C. §120 that a continuing application must be filed "before the patenting" of the parent application.
- This contention, if successful, invalidates the claimed 1998 priority date, making the Walker reference, published in 2000, available as prior art.

Petitioner requested the institution of an inter partes review and the cancellation of claims 1-31 of Patent 7,076,624 as unpatentable under 35 U.S.C. §§ 102 and 103.