US 7152182

Patent Overview: US7152182 — Data Redundancy System and Method

Title: Data redundancy system and method

Assignee: Valtrus Innovations Ltd (current assignee per source); original assignee Hewlett Packard Development Co LP

Inventors: Minwen Ji, Alistair Veitch, John Wilkes

Key dates: Priority and filing — 2003-06-06; publication — 2006-12-19; expiration adjusted — 2025-01-07; status — Expired – Lifetime

Technical field: The invention "relates to the field of data storage," specifically "techniques for redundant data storage."

Purpose: Remote mirroring is used to cope with storage system failures. A "primary" or "local" copy of data is updated as it is accessed by an application program, and a redundant "secondary" or "slave" copy, usually at a remote site, is updated as well. If the primary copy becomes unavailable, "the data can be restored from the secondary copy, or accessed directly from there."

Plain-language scope (based on the supplied excerpt): A primary data storage facility stores a primary copy of data, and a secondary facility stores data redundant of that primary copy. The primary facility includes a first redundancy appliance that receives a sequence of write requests and stores data for those requests in storage associated with the primary storage facility. A second redundancy appliance "shadows" the first and "assumes the role of the first redundancy appliance in the event of a fault at the first redundancy appliance," thereby increasing fault tolerance. The second appliance may maintain a shadow copy of the data stored by the first appliance and access that shadow copy upon assuming the first appliance's role; alternatively, it may access the data stored by the first appliance at that time.

The excerpt references FIG. 1, which "illustrates a computer system including a primary data storage facility and a secondary data storage" (text truncated at that point).

Source: https://patents.google.com/patent/US7152182/en

What the excerpt does not establish: It contains no claims text, no full figure content, and no description of detailed operation, fault-detection mechanisms, or write-order handling. It also does not establish validity, infringement, or prior-art relationships.