PCPI Differencing for Metadata Search Database Updates

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Solution Overview

Problem

Current file systems face inefficiencies in rapidly updating metadata databases, leading to inconsistent data and significant processing time, especially in large storage systems, due to the need for frequent file system crawls which impact performance and require direct access to all data containers.

Innovation Solution

The implementation of a system and method using persistent consistency point image (PCPI) differencing to quickly identify changes in metadata, allowing for accelerated updates to metadata search databases by generating and maintaining metadata search databases through a search agent that serially reads inode files and log files to maintain consistency with the file system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If file system crawls are performed frequently to update metadata databases, then database consistency is improved, but system performance deteriorates and processing time increases

Engineering Contradiction:
Improvedatabase consistencyVSAvoidsystem performance
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The system performs preliminary actions by creating consistency point images at predetermined intervals before metadata updates are needed. These images capture the state of data containers at specific points in time, allowing subsequent differencing operations to quickly identify changes without requiring full crawls of the file system.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention extracts only the necessary information for metadata updating by comparing consistency point images to identify changed data containers. Instead of examining all data containers during each update cycle, the system extracts change information through image differencing, significantly reducing processing requirements.

Inventive Principle:
Principle #2Taking out (Extraction)

2Loss of information

If file system crawls are performed to update metadata, then complete metadata information is obtained, but processing time and computational resources increase significantly

Engineering Contradiction:
Improvemetadata completenessVSAvoidprocessing time
Core Design Contradiction:
Loss of informationVSLoss of time

Solution Approach 1:

The system creates copies of file system state information in the form of consistency point images at predetermined intervals. These images serve as snapshots that can be stored and compared later, eliminating the need to perform time-consuming crawls of the actual file system during metadata update operations.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

Consistency point images are generated in advance at predetermined intervals, capturing the state of data containers before updates occur. This preliminary capture allows subsequent differencing operations to quickly identify changes without requiring access to or examination of the actual data containers during the update process.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If direct access to all data containers is performed during metadata updates, then accurate metadata is obtained, but system performance and availability are impacted

Engineering Contradiction:
Improvemetadata accuracyVSAvoidsystem availability
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The invention extracts metadata update information indirectly by comparing consistency point images rather than directly accessing data containers during updates. The differencing operation identifies changed containers through image comparison, obtaining accurate metadata information without requiring direct access to the actual data containers.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system performs preliminary capture of file system state in consistency point images before updates occur. This allows subsequent metadata updates to be performed by comparing images rather than by directly accessing and examining data containers, maintaining accuracy while avoiding performance impacts.

Inventive Principle:
Principle #10Preliminary action

4Reliability

If frequent metadata updates are performed to maintain consistency, then database reliability is improved, but the frequency and duration of crawls increase system overhead

Engineering Contradiction:
Improvemetadata consistencyVSAvoidsystem overhead
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system maintains reliability by creating and comparing copies of file system state (consistency point images) rather than performing crawls of the actual file system. These image copies can be stored efficiently and compared using differencing algorithms, reducing the computational overhead associated with frequent updates.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

Consistency point images are created at predetermined intervals rather than continuously or on every change event. This periodic creation of images, combined with differencing-based updates, maintains metadata consistency while reducing the frequency and complexity of update operations compared to traditional crawl-based approaches.

Inventive Principle:
Principle #19Periodic action

Data Source

PatentUS7693864B1System and method for quickly determining changed metadata using persistent consistency point image differencing
Publication Date: 2010.04.06 NETAPP INC
  • US7693864B1 patent drawing
  • US7693864B1 patent drawing
  • US7693864B1 patent drawing

AI summary

A system and method accelerates update of a metadata search database using PCPI differencing. After first populating the search database, a search agent generates a PCPI and utilizes a PCPI differencing technique to quickly identify changes between inode files of first and second PCPIs. The differences are noted as modified metadata and are written to a log file, which is later read by the search agent to update the search database.