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Comparing DR Items

You can check the data consistency by comparing DR items at the object level or data level in the service and DR databases.

  • Object-level comparison: compares databases, events, indexes, tables, views, stored procedures, functions, and triggers.
  • Data-level comparison: compares rows and values of tables. To ensure that the comparison results are valid, compare data during off-peak hours by select Start at a specified time or compare cold data that is infrequently modified.

Prerequisites

You have logged in to the DRS console.

Procedure

  1. On the Disaster Recovery Management page, click the target DR task in the Task Name/ID column.
  2. On the Disaster Recovery Comparison tab, compare the service and DR databases.

    1. Check the integrity of the database object.
      Click Validate Objects. On the Object-Level Comparison tab, click Compare. Wait for a while and click , and view the comparison result of each comparison item.
      Figure 1 Comparing objects

      Locate a comparison item you want to view and click View Details in the Operation column.

    2. After the check is complete, compare the number of rows.

      On the Data-Level Comparison tab, click Create Comparison Task. In the displayed dialog box, specify Compute Resource, Comparison Type, Execution Time, and Object. Then, click OK.

      Figure 2 Creating a comparison task
      • Comparison Type: compares rows and values.
      • Compute Resource: This function affects the resources used by value comparison on the source database. Compute resources are classified into DRS compute resources and database compute resources.
        • On DRS: DRS reads data from both the source and destination databases first and then compares the data, which increases the I/O read load on the source database but does not affect the performance of source CPU and memory. This option is suitable for value comparison of cold data in static tables during service running.
        • On databases: DRS directly compares data on the source and destination databases using their own CPU, memory, and I/O resources. This option is suitable for value comparison in non-service window when no data changes occur. The comparison on database is faster than the comparison on DRS.
      • Comparison Time: You can select Start upon task creation or Start at a specified time. There is a slight difference in time between the source and destination databases during synchronization. Data consistency may occur. You are advised to compare migration items during off-peak hours for more accurate results.
      • Object: You can select objects to be compared based on the scenarios.
      • Data-level comparison cannot be performed for tasks in initialization.
    3. After the comparison creation task is submitted, the Data-Level Comparison tab is displayed. Click to refresh the list and view the comparison result of the specified comparison type.
      Figure 3 Viewing the data-level comparison result
    4. To view the comparison details, locate the target comparison type and click View Results in the Operation column. On the displayed page, locate a pair of service and DR databases, and click View Details in the Operation column to view detailed comparison results.
      Figure 4 Viewing comparison details

      You can also view comparison details of canceled comparison tasks.