Prior art — US Patent 7490263

Most Relevant Prior Art for US7490263

The following prior art documents were cited by US Patent 7490263. The analysis focuses on patents that disclose mechanisms for defect management, error recovery, and data verification within storage devices, particularly those that might anticipate the core inventive concepts of US7490263 as defined by its independent claims (Claims 1 and 6).

The key novelty of US7490263 lies in the storage device's active enforcement of write recovery by:

Maintaining a reassignment log of defective LBAs requiring controller-initiated reassignment (including unreported errors).
Automatically verifying data after a "write without verify" command if the LBA is in the log.
Reporting an unrecovered write error to the storage controller upon auto-verify failure, thereby triggering the controller's write recovery procedure, which includes reassignment.

Many of the cited patents broadly cover defect management and error handling. The most relevant prior art would be those that detail how defects are identified, how reassignments are managed (especially involving the host/controller), and how write verification or re-attempts are handled in the presence of known or suspected defects.

Given the extensive list of cited patents, I will focus on the ones that appear most relevant based on their titles and publication dates relative to US7490263's priority date (January 17, 2006). Patents with titles explicitly mentioning "defect maps," "error recovery," "reassignment," and "verification" will be prioritized for detailed description and anticipation analysis.

Detailed Analysis of Selected Prior Art

1. US6968413B2 - System, method and program product for recovering from errors in storing and retrieving data on a storage medium using a primary defect map and a secondary defect map

Full Citation: US6968413B2, "System, method and program product for recovering from errors in storing and retrieving data on a storage medium using a primary defect map and a secondary defect map," issued November 22, 2005.
Publication/Filing Date: Issued: November 22, 2005; Filed: May 12, 2003.
Brief Description: This patent describes a system and method for error recovery in a storage medium using a primary defect map (PDM) and a secondary defect map (SDM). The PDM lists factory-detected defects, while the SDM dynamically records defects detected during read/write operations. When an error occurs during a read, the system attempts recovery. If unsuccessful, the defect is added to the SDM, and data may be relocated. If an error occurs during a write, the system writes the data to an alternate location and updates the SDM. The system involves a storage control unit and a storage device, where defect mapping and error recovery are managed.
Potential Anticipation (35 U.S.C. § 102): US6968413B2 describes a storage device maintaining defect maps (analogous to a "reassignment log" in concept for tracking defective blocks) and performing error recovery. It covers the detection of errors during read/write operations and the reallocation of defective blocks. However, it does not explicitly disclose the unique combination of steps found in Claim 1 and Claim 6 of US7490263, specifically:
- The "reassignable check module" determining if an LBA of a "write without verify" command is in a reassignment log that stores LBAs for which the storage device was unable to reassign and recommends a reassignment by the storage controller.
- The "auto verify module" automatically verifying data written at such a previously identified reassignable LBA (from the log).
- The "error posting module" reporting an unrecovered write error to the storage controller in response to the auto-verify failure to specifically trigger a storage controller write recovery procedure including reassignment.
  While US6968413B2 has defect lists and recovery, the specific trigger mechanism and the device-enforced controller action based on a "write without verify" command on a pre-identified, device-logged, controller-reassignable defective block is not explicitly taught. Therefore, it is unlikely to fully anticipate the unique combination of these elements.

2. US6792518B1 - System, method and program product for recovering from errors in storing and retrieving data on a storage medium using a primary defect map and a secondary defect map

Full Citation: US6792518B1, "System, method and program product for recovering from errors in storing and retrieving data on a storage medium using a primary defect map and a secondary defect map," issued September 14, 2004.
Publication/Filing Date: Issued: September 14, 2004; Filed: December 18, 2000.
Brief Description: This patent describes an error recovery system for storage media that uses both a primary defect map (for initial defects) and a secondary defect map (for defects found during normal operation). When an uncorrectable read error occurs, the data is rewritten to a new location, and the secondary defect map is updated. If a write error occurs, the data is rewritten to an alternate location. The system aims to minimize data loss by remapping defective areas.
Potential Anticipation (35 U.S.C. § 102): Similar to US6968413B2, this patent details defect management and reallocation using defect maps within the storage device. It covers error detection during read and write operations and subsequent reallocation. However, it lacks the specific mechanism of US7490263 where a "write without verify" command to a known defective LBA in a device-maintained log triggers an auto-verify by the device, and a subsequent error report to explicitly force the controller to perform a reassignment. The emphasis in US6792518B1 is on the drive managing the reallocation, not on the drive forcing the controller to perform a write recovery due to a rediscovered defect during a write operation that the controller might otherwise ignore.

3. US6647463B1 - Method and apparatus for updating defect maps for disk drives

Full Citation: US6647463B1, "Method and apparatus for updating defect maps for disk drives," issued November 11, 2003.
Publication/Filing Date: Issued: November 11, 2003; Filed: May 29, 2001.
Brief Description: This patent focuses on managing and updating defect maps in disk drives. It describes a method for detecting new defects during normal operation and incorporating them into a defect map, which is then used to redirect access to defective sectors to spare sectors. This includes updating the defect map when a defective sector is successfully reallocated.
Potential Anticipation (35 U.S.C. § 102): This patent clearly teaches the use of defect maps and their updates when defects are found and reallocated. This element of a "reassignment log" that stores LBAs of defective blocks and removes them when reassigned is present in US6647463B1. However, this patent does not describe the "auto verify" step specifically triggered by a "write without verify" command to a known defective LBA in the log, nor the subsequent reporting of an unrecovered write error to the storage controller to enforce a write recovery procedure. Its focus is on the drive's internal management of defects.

4. US6460114B1 - Data transfer system and method for recovering from an error in data transmission

Full Citation: US6460114B1, "Data transfer system and method for recovering from an error in data transmission," issued October 1, 2002.
Publication/Filing Date: Issued: October 1, 2002; Filed: December 21, 1999.
Brief Description: This patent describes a data transfer system that handles errors during data transmission, particularly in a disk drive controller. It outlines methods for detecting errors (e.g., CRC errors), performing retries, and, if errors persist, invoking a recovery process that could involve marking a sector as bad and reassigning it. The system typically involves the controller managing the error recovery.
Potential Anticipation (35 U.S.C. § 102): US6460114B1 deals with error recovery, including detecting persistent errors and reassigning bad sectors. This aligns with the general problem US7490263 seeks to solve. However, US7490263 specifically addresses the scenario where the storage device enforces a write recovery when the storage controller might not otherwise initiate it, particularly for previously identified but un-reassigned defective blocks receiving a "write without verify" command. US6460114B1 doesn't explicitly teach the storage device's "reassignable check module," "auto verify module," and "error posting module" working in concert to proactively force the storage controller's hand in write recovery for such a specific sequence of events.

Conclusion on Most Relevant Prior Art

While the cited prior art patents, such as US6968413B2, US6792518B1, US6647463B1, and US6460114B1, disclose various aspects of defect management, error detection, and reallocation in storage devices, they do not appear to fully anticipate the specific combination of features claimed in US7490263, particularly in Claims 1 and 6.

The distinguishing features of US7490263 appear to be:

The storage device maintaining a "reassignment log" specifically for LBAs that it recommends for controller reassignment (due to the device's inability to do so automatically or lack of valid data) and that the controller has not yet acted upon.
The automatic verification (auto verify) by the storage device when a "write without verify" command targets an LBA found in this specific reassignment log.
The storage device reporting an unrecovered write error back to the controller due to the auto-verify failure to compel the storage controller to initiate its own write recovery procedure, including reassignment, for a defect the controller may have otherwise overlooked or not remembered.

The prior art broadly discusses defect maps and reallocation, but not this precise mechanism of the storage device enforcing the controller's write recovery for previously noted, un-reassigned defective blocks during a seemingly benign "write without verify" operation. Therefore, while elements of defect management are present in the prior art, the specific "enforcement" mechanism of US7490263 appears to differentiate it.