PTAB

IPR2025-00202

Liberty Mutual Insurance Co v. Intellectual Ventures II

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Root Image Caching and Indexing for Block-Level Distributed Application Management
  • Brief Description: The ’844 patent discloses a system for distributing application environments to multiple compute nodes using a “root/leaf” storage architecture. The system stores a common, read-only “root image” on a first storage unit and stores node-specific changes or additions in separate “leaf images” on second storage units, which allegedly improves storage efficiency and boot times.

3. Grounds for Unpatentability

Ground 1: Obviousness over Sapuntzakis and Holzmann - Claims 1-13 are obvious over Sapuntzakis in view of Holzmann.

  • Prior Art Relied Upon: Sapuntzakis (a 2002 journal article entitled “Optimizing the Migration of Virtual Computers”) and Holzmann (Application # 2005/0283597).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Sapuntzakis disclosed the core architecture of the ’844 patent. Sapuntzakis taught a system for migrating virtual computers (“capsules”) using a hierarchy of copy-on-write (COW) disks, where a complete “root disk” serves as a base and child “capsules” store only the differences. This directly maps to the claimed root/leaf structure where leaf images contain only changes and new data blocks. Sapuntzakis also disclosed using local "shadow COW disks" to cache blocks from remote disks, teaching the caching limitation. Holzmann was cited to provide more explicit teachings on caching boot image data from a single OS image to speed access for multiple servers, thereby reinforcing the caching limitations of claims 1 and 7.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine these references to improve performance. Petitioner asserted that both references address the efficient network-based management of OS images and both disclose caching to improve efficiency. A POSITA seeking to optimize the system in Sapuntzakis would have been motivated to incorporate the more detailed and conventional caching techniques of Holzmann to improve the speed and efficiency of data access.
    • Expectation of Success: A POSITA would have a high expectation of success, as applying a well-understood technique like caching (Holzmann) to a distributed storage system (Sapuntzakis) would predictably result in improved performance.

Ground 2: Obviousness over Sapuntzakis and Federwisch - Claims 14-27 are obvious over Sapuntzakis in view of Federwisch.

  • Prior Art Relied Upon: Sapuntzakis (a 2002 journal article) and Federwisch (Application # 2003/0182313).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner relied on Sapuntzakis to teach the fundamental root/leaf architecture and caching, as described in Ground 1. To meet the additional limitations of claims 14-27, which require indexing file systems and sharing indexing results between compute nodes, Petitioner cited Federwisch. Federwisch disclosed a system for mirroring changes between data snapshots by comparing a “logical file block index of each snapshot.” It explicitly taught creating and comparing indexes to identify changed data blocks and sharing this index information, mapping directly to the indexing limitations.
    • Motivation to Combine: Petitioner argued that since Sapuntzakis already disclosed a form of indexing (a hash table for cached entries), a POSITA would be motivated to improve upon this with more robust, well-known indexing techniques for managing the entire storage system. A POSITA would combine Federwisch's block-level indexing methods with the Sapuntzakis system to more efficiently locate and manage data blocks across the root and leaf images.
    • Expectation of Success: Success would be expected because indexing is a fundamental and well-understood computer science technique for improving data retrieval, and applying it to the system of Sapuntzakis was a straightforward design choice.

Ground 3: Obviousness over Birse and Holzmann - Claims 1-13 are obvious over Birse in view of Holzmann.

  • Prior Art Relied Upon: Birse (Patent 7,089,300) and Holzmann (Application # 2005/0283597).

  • Core Argument for this Ground:

    • Prior Art Mapping: As an alternative to Sapuntzakis, Petitioner argued that Birse taught the claimed root/leaf architecture. Birse described a net-booted environment where a server provides a read-only master copy of an OS (the root image) to multiple client computers. User customizations and modifications were stored in separate, client-specific “shadow volumes” (the leaf images), which contained only the portions of the OS modified by the user. Birse’s block device driver dynamically merged the master copy and shadow volume. Holzmann was again used to supply the explicit caching limitations for booting multiple clients.
    • Motivation to Combine: A POSITA would combine Birse and Holzmann to improve the performance of Birse's net-booted system. While Birse disclosed a functional system, its performance would be enhanced by implementing a more sophisticated caching mechanism for the boot images. A POSITA would have looked to known solutions like Holzmann, which detailed caching for this exact purpose.
    • Expectation of Success: The combination would yield the predictable result of faster boot times and reduced network load, as caching is a standard method for achieving these goals.

  • Additional Grounds: Petitioner asserted an additional obviousness challenge for claims 14-27 based on the combination of Birse and Federwisch, applying the indexing teachings of Federwisch to the base system disclosed in Birse.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued against discretionary denial under §325(d), stating that the prior art references and combinations relied upon in the petition were not substantively addressed or, in some cases, even cited by the Examiner during prosecution of the ’844 patent.
  • Petitioner also argued against discretionary denial under Fintiv and §314(a). Petitioner asserted that the parallel district court litigation was in a very early stage, with no Markman hearing scheduled, fact discovery remaining open, and a trial date far in the future (September 2025). Furthermore, it was argued that only 2 of the 27 challenged claims were asserted in the litigation, meaning the IPR would be a more efficient forum to resolve the patentability of the vast majority of the claims.

5. Relief Requested

  • Petitioner requests institution of an IPR and cancellation of claims 1-27 of the ’844 patent as unpatentable.