PTAB

IPR2019-00598

NetApp Inc v. KOM Software Inc

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1. Case Identification

2. Patent Overview

  • Title: Method of Providing Restricted Write Access on a Data Storage Medium
  • Brief Description: The ’624 patent discloses a method and system for restricting file access on a data storage medium. The invention uses a "trap layer" (also called a "filter layer") disposed between an application layer and a file system layer to intercept access requests, determine whether the operation is supported, and then allow, modify, or deny the operation transparently to the user and the invoking application.

3. Grounds for Unpatentability

Ground 1: Anticipation by Nagar - Claims 1-11 and 22-31 are anticipated by Nagar under 35 U.S.C. § 102.

  • 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 textbook on the Windows NT operating system, disclosed every element of the challenged claims. Nagar’s detailed description of a "filter driver" was asserted to be the claimed "trap layer," as it functions as an intermediate driver that intercepts I/O requests between an application and the file system. Petitioner mapped Nagar’s teachings to show this filter driver intercepts operations (e.g., read, write) on logical portions of storage (e.g., files, mounted logical volumes), applies access privileges by allowing or denying operations based on certain criteria (such as virus detection), and does so transparently to the user and other system layers, thus anticipating the independent claims. The dependent claims were also allegedly disclosed, as Nagar described applying these methods to files and directories, using file names as data identifiers, and intercepting various I/O operations like read and create.

Ground 2: Anticipation by Vossen - Claims 1-11 and 22-31 are anticipated by Vossen under 35 U.S.C. § 102.

  • Prior Art Relied Upon: Vossen (Patent 6,026,402).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Vossen taught a method for restricting a process’s access to a subset of a computer’s file system, anticipating the claims. Vossen’s "process restriction filter driver" was presented as the claimed "trap layer," as it is a layer above the file system driver that intercepts all I/O Request Packets (IRPs). This filter driver allegedly applies access privileges by checking data structures to determine if a process is permitted to access a specific file system sub-hierarchy, thereby enabling or restricting operations. Petitioner contended that Vossen’s system operated transparently to the application and regardless of user identity, meeting all limitations of the independent claims. Vossen’s disclosure of hierarchical file systems with files and directories identified by path names was argued to meet the limitations of the dependent claims.

Ground 3: Obviousness over Vossen and Willman - Claims 10 and 31 are obvious over Vossen in view of Willman.

  • Prior Art Relied Upon: Vossen (Patent 6,026,402) and Willman (Patent 5,363,487).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner asserted that dependent claims 10 and 31, which depend from claims reciting hierarchical storage media (claim 8), were obvious over the combination of Vossen and Willman. Vossen was argued to teach the base system of claim 8, including applying access privileges to logical portions of a storage medium (e.g., a file within a directory). Willman was argued to supply the missing element: a "data identifier" that "comprises newly created data." Willman discloses techniques for interfacing with dynamically changing storage media, including generating new identifiers (e.g., a "volume identifier" or "Fnode") for newly mounted media or newly created files and directories.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Vossen's access control method with Willman's dynamic media handling to apply file access restrictions to newly created data. Both references address file management via system drivers, making the combination a predictable solution to a known need.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success in implementing Willman’s techniques for identifying new data within Vossen's filtering framework, as it involved applying known file management principles to yield the predictable result of secure access control for new files and volumes.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including alternative arguments that Nagar and Vossen individually render the claims obvious under §103. Petitioner also asserted that claims 10 and 31 are obvious over Vossen combined with Nagar. These grounds relied on similar prior art teachings and motivations for combining known filter driver functionalities.

4. Key Claim Construction Positions

  • "trap layer" (claims 1, 12, 22): This term was central to the petition.
    • Petitioner’s Proposed Construction: Argued for a structural definition of "trap layer" as a "Windows NT filter driver logically disposed between the application layer and the file system layer."
    • Patent Owner’s Position (as characterized by Petitioner): Noted that the Patent Owner advocated for the term’s plain and ordinary meaning in related litigation, but also suggested a functional limitation where the trap layer "limits operations performed on the storage medium to those supported by the read/write device."
    • Core Dispute: Petitioner argued that its invalidity arguments prevailed even under the Patent Owner's broader construction. However, Petitioner contended the Patent Owner’s functional limitation was an improper attempt to read a limitation from the specification into the claims, arguing the term should be given its full, ordinary meaning as understood by a POSITA, which encompasses the structures described in the prior art.

5. Relief Requested

  • Petitioner requested the institution of an inter partes review and the cancellation of claims 1-11 and 22-31 of the ’624 patent as unpatentable under 35 U.S.C. §§ 102 and 103.