After a data migration project starts, you can view the project metrics on the details page of the project, such as the basic information, and project progress and status.
Access the details page
Log on to the OMS console.
In the left-side navigation pane, click Data Migration.
On the Data Migration page, click the name of the target project. On the details page that appears, view the basic information and migration details of the project.
On the Data Migration page, you can search for data migration projects by tag, status, type, or keywords. A data migration project may be in any of the following states:
Not Started: The data migration project has not been started. You can click Start in the Actions column to start the project.
Running: The data migration project is in progress. You can view the data migration plan and current progress on the right.
Modifying: The migration objects in the migration project are being modified.
Integrating: The data migration project of the modified migration object is being integrated with the migration object modification task.
Paused: The data migration project is manually paused. You can click Resume in the Actions column to resume the project.
Failed: The data migration project has failed. You can view where the failure occurred on the right. To view the error messages, click the project name to go to the project details page.
Completed: The data migration project is completed and OMS has migrated the specified data to the destination database in the configured migration mode.
Releasing: The data migration project is being released. You cannot edit a data migration project in this status.
Released: The data migration project is released. After the project is released, OMS terminates the current migration and incremental synchronization project.
View basic information
The Basic Information section shows you the basic information related to the current migration project.
| Parameter | Description |
|---|---|
| ID | The unique identifier of the migration project. |
| Migration Type | The migration type chosen when creating the migration project. |
| Alert Level | The alert level of the data synchronization project. OMS supports the following alert levels: No Protection, High Protection, Medium Protection, and Low Protection. For more information, see Alert settings. |
| Created By | The user who created the current data migration project. |
| Created At | The creation time of the current migration project. |
| Concurrency for Full Migration | The value can be Smooth, Normal, or Fast. The amount of resources to be consumed by a full data migration task varies based on the migration performance. |
| Full Verification Concurrency | The value can be Smooth, Normal, or Fast. Resources consumed at the source and destination databases vary based on the specified concurrency. |
| Connection Details | Click Connection Details to view the information about the connection between the source and destination databases of the data migration project. |
You can perform the following operations:
View migration objects
Click View Objects in the upper-right corner to view the list of migration objects for the current project. You can also modify the migration objects of an ongoing data migration object. For more information, see View and modify migration objects.
View the component monitoring metrics
Click View Component Monitoring in the upper-right corner to view the information about the Store, Incr-Sync, Full-Import, and Full-Verification components. You can perform the following operations on the components:
Start a component: Click Start in the Actions column of the target component. In the dialog box that appears, click OK.
Pause a component: Click Pause in the Actions column of the target component. In the dialog box that appears, click OK.
Update a component: Click Update in the Actions column of the target component. On the Update Configuration page, modify the configurations and then click Update.
Notice
The system restarts after you update the component. Proceed with caution.
View logs: Click View Logs in the Actions column of the target component. The View Logs page displays the latest logs. You can search for, download, and copy the logs.
View or modify parameter configurations
For a data migration project in the Running state, click the More icon in the upper-right corner and then select Settings from the drop-down list to view the parameters of the data migration project when it was created.
For a data migration project in the Not Started, Paused, or Failed state, click the More icon in the upper-right corner and then select Modify Parameter Configurations from the drop-down list. In the Modify Parameter Configurations dialog box, modify the parameters, and click OK.
The parameters that can be modified vary with the type of the data migration project and the stage of the task.
Download object settings
OMS allows you to download configuration information of data migration projects and import migration project settings in batches. For more information, see Download and import the settings of migration objects.
View migration details
The Migration Details section shows you the details of all the sub-projects in your migration project, including the current state and progress, start and end time, and the total elapsed time, etc.
Schema migration
The definitions of data objects, such as tables, indexes, constraints, comments, and views, are migrated from the source database to the destination database. Temporary tables are automatically filtered out. When the source database is not OceanBase Database, the data types and SQL syntax are automatically converted and assembled according to the syntax definition standards of the destination tenant of OceanBase Database, and then replicated to the destination database.
When you advance to the forward switchover step in a data migration project, OMS will automatically drop the hidden columns and unique indexes based on the type of the data migration project. For more information, see Hidden column mechanisms.
You can view the overall status, start time, completion time, total time consumed, and table and view migration progress for a schema migration project on the Schema Migration page. You can also perform the following operations on an object:
View Creation Syntax: On the Database or Table tab, click View next to the target object to view the creation syntax of a database, table, or index.
If the object creation syntax is fully compatible, the DDL syntax executed on the OBServer node is displayed. Incompatible syntax is converted before it is displayed.
Modify Creation Syntax and Try Again: View the error information, check and modify the definition of the conversion result of a failed DDL statement, and then migrate the data to the destination again.
Retry/Retry All Failed Objects: You can retry failed schema migration tasks one by one or retry all failed tasks at a time.
Skip/Batch Skip: You can skip failed schema migration tasks one by one or skip multiple failed tasks at a time. To skip multiple objects at a time, click Batch Skip in the upper-right corner. If you skip an object, its index is also skipped.
Remove/Batch Remove: You can remove failed schema migration tasks one by one or remove multiple failed tasks at a time. To remove multiple failed tasks at a time, click Batch Remove in the upper-right corner. If you remove an object, its index is also removed.
View Details: The DDL statements executed on the OBServer node and the execution error information of a failed schema migration task are displayed.
Full migration
Full data migration migrates the existing data of the source database to the corresponding tables in the target database. You can filter information based on the target and source databases, or select View Objects with Errors to filter out objects that hinder the overall migration progress. You can also view related information on the Table Objects, Table Indexes, and Full Migration Performance tabs. The status of a full migration task changes to Completed only after the table objects and table indexes are migrated.
On the Table Objects tab, you can view the names, source and destination databases, estimated data volume, migrated data volume, and status of tables.
On the Table Indexes tab, you can view the table objects, source and destination databases, creation time, end time, time consumed, and status. You can also view the index creation syntax and remove unwanted indexes.
On the Migration Performance tab, you can view diagrams on the performance of the current migration project, including the RPS, migration traffic, and read/write time of the source or target database, to help you identify performance-related issues, if any.
You can combine full migration with incremental synchronization to ensure data consistency between the source and destination databases. If any objects fail to be migrated during full migration, the causes of the failure are displayed.
Notice
If you do not select Schema Migration for Migration Type, OMS migrates the fields in the source database that match those in the destination database during full migration, without checking whether the schemas are consistent.
After full migration is completed and the subsequent step has started, you cannot click Rerun next to the target Full-Verification component on the page displayed after you choose O&M and Monitoring > Component > Full-Verification.
Incremental synchronization
After incremental synchronization starts, the data migration service synchronizes the data that has been changed (added, modified, or deleted) in the source database to the corresponding tables in the target database. When services continuously write data to the source database, OMS starts the incremental data pull module to pull incremental data from the source instance, parses and encapsulates the incremental data, and then stores the data in OMS. After that, OMS starts the full data migration.
After the full data migration task is completed, OMS starts the incremental data replay module to pull incremental data from the incremental data pull module. The incremental data is synchronized to the destination instance after being filtered, mapped, and converted. If an Incr-Sync exception occurs after you execute a DDL statement on the source database and the data migration project fails, a page appears, displaying the DDL statement that causes the project failure and the Skip button. You can skip the operation by clicking Skip on the page.
Notice
This operation may lead to data schema inconsistency between the source and destination databases. Proceed with caution.
For a Running data migration project, you can view its latency, current timestamp, and incremental synchronization performance in the incremental synchronization section. The latency is displayed in the following format: X seconds (updated Y seconds ago). Normally, Y is less than 20.
For a Paused or Failed data migration project, you can enable the DDL/DML statistics feature to collect statistics on the database operations performed after this feature is enabled. You can also view the specific information about incremental synchronization objects and the incremental synchronization performance.
The Synchronization Object Statistics tab displays the statistics about table-level DML statements executed for each incremental synchronization object in the current project. The numbers displayed in the Change Sum, Delete, Insert, and Update fields in the section above the Synchronization Object Statistics tab are the sums of the corresponding columns on this tab.
The Incremental Synchronization Performance tab displays the following content:
Latency: the delay in the source-side incremental changes being synchronized to the target side, measured in seconds.
Migration traffic: the traffic throughput of incremental data synchronization from the source to the destination, in KB/s.
Average execution time: the average execution time per SQL statement, measured in milliseconds.
Average commit time: the average commit time per transaction, measured in milliseconds.
RPS: the number of records processed per second.
When you create a data migration project, we recommend that you specify related information such as the alert level and alert frequency, to help you understand the project status. OMS provides low-level protection by default. You can modify the alert level based on your business requirements. For more information, see Alert settings.
When the incremental synchronization latency exceeds the specified alert threshold, the incremental synchronization status stays at Running and the system does not trigger any alerts.
When the incremental synchronization latency is less than or equal to the specified alert threshold, the incremental synchronization status changes from Running to Monitoring. After the incremental synchronization status changes to Monitoring, it will not change back to Running when the latency exceeds the specified alert threshold.
Full verification
After the full data migration and incremental data migration are completed, OMS automatically initiates a full data verification task to verify the data tables in the source and destination databases.
Notice
If you do not select Schema Migration for Migration Type, OMS verifies the fields in the source database that match those in the destination database during full verification, without checking whether the schemas are consistent.
During the full data verification, if you perform the
create,drop,alter, orrenameoperation on the source tables, the full data verification may exit.
You can also initiate custom data verification tasks in the incremental data synchronization process. On the Full Verification page, you can view the overall status, start time, end time, total consumed time, estimated total number of rows, number of migrated rows, real-time traffic, and RPS of the full verification task.
The Full Verification page contains the Verified Objects and Full Verification Performance tabs.
On the Verified Objects tab, you can view the verification progress and verification object list.
You can view the names, source and destination databases, full data verification progress and results, and result summary of all migration objects.
You can filter migration objects by source or destination database.
You can select View Completed Objects Only to view the basic information of objects that have completed schema migration, such as the object names.
You can choose Reverify > Restart Full Verification to run a full verification again for all migration objects.
Take note of the following items for tables with inconsistent verification results:
If you need to reverify all data in the tables, choose Reverify > Reverify Abnormal Table.
If you need to reverify only inconsistent data, choose Reverify > Verify Only Inconsistent Records.
Notice
Correction operations are not supported if the source database has no corresponding data.
On the Full Verification Performance tab, you can view the graphs of performance data such as the RPS and verification traffic of the source and destination databases and performance benchmarks. Such information can help you identify performance issues in a timely manner.
OMS allows you to skip full verification for a project that is being verified or has failed verification. On the Full Verification page, click Skip Full Verification in the upper-right corner. In the dialog box that appears, click OK.
Notice
If you skip full data verification, you cannot resume the verification task for data comparison and correction. You can only clone the current project to initiate full data verification again. Therefore, proceed with caution.
After the full verification is completed, you can click Go To Next Stage to start a forward switchover. After you enter the switchover process, you cannot recheck the current verification task to compare or correct data.
Forward switchover
Forward switchover is an abstract and standard process of traditional system cutover and does not involve the switchover of application connections. This process includes a series of tasks that are performed by OMS for application switchover in a data migration project. You need to make sure that the entire forward switchover process is completed before the application connections are switched over to the destination database.
Forward switchover is indispensable in data migration. Through forward switchover, OMS can verify that forward data migration is completed. You can then start the reverse incremental migration component. Forward switchover involves the following jobs:
You need to confirm that data migration is completed and wait until there is no latency in forward synchronization.
OMS will automatically supplement CHECK constraints, FOREIGN KEY constraints, and other objects that are ignored in the schema migration phase when the destination is an Oracle database, an Oracle tenant of OceanBase Database, or a DB2 LUW database.
OMS will automatically drop the additional hidden columns and unique indexes that the migration depends on.
This operation is performed only for data migration between an Oracle database and an OceanBase database or between OceanBase databases. For more information, see Hidden column mechanisms.
You need to supplement triggers, functions, stored procedures, and other database objects at the source that are not supported by OMS to the destination.
You need to disable triggers and FOREIGN KEY constraints at the source when reverse incremental migration is selected for a data migration project.
The forward switchover procedure is as follows:
Start forward switchover
This step aims to confirm the start of forward switchover. No related operation is actually performed in the background. After you confirm that data migration is completed, you can click Start Forward Switchover to start the forward switchover process for business cutover.
Notice
Before you start forward switchover, make sure that writing has been stopped at the source.
Perform switchover precheck
This step checks the following items before forward switchover:
Latency between the source and destination. If the latency is within 15s, this item passes the check.
Write privilege of the migration account on the source. If reverse incremental migration is selected for a data migration project, you need to check whether the migration account configured for the source has the privilege to write data, to ensure that data can be properly written during reverse incremental migration.
Read privilege of the migration account on the destination. If reverse incremental migration is selected for a data migration project, you need to check whether the migration account configured for the destination has the privilege to read data, to ensure that data can be properly read from the destination during reverse incremental migration.
Incremental logs at the destination. If reverse incremental migration is selected for a data migration project, you need to check whether the incremental log configurations at the destination meet the log pull requirements during reverse incremental migration.
If the switchover precheck is passed, OMS automatically proceeds to the next step. If the switchover precheck fails, OMS provides two options: Retry and Skip.
Notice
If you choose to skip this step, issues such as data loss at the destination or failure of reverse incremental migration may occur. Proceed with caution.
Start the destination Store
Note
This step is displayed only when a data migration project has the reverse incremental migration phase.
If the forward switchover precheck is passed, OMS automatically starts the incremental log pull service for the destination to obtain the DML and DDL operations performed at the destination and parse and save related log data, to prepare for reverse incremental migration. This step lasts about three to five minutes.
Confirm that writing has stopped at the source
This step aims to confirm that the source has no continuous business writes. If you confirm that the source has no new data, click OK to proceed to the next step.
Confirm that the destination is synchronized to the writing stop timestamp of the source
This step aims to confirm that the destination is synchronized to the timestamp when writing is stopped at the source. If this step is in progress or fails and the synchronization is not completed after a long period, you can click Skip.
Notice
If you choose to skip this step, data inconsistency may occur between the source and destination. Proceed with caution.
Stop forward synchronization
This step aims to stop the forward synchronization service. After the service is stopped, the database changes made at the source are no longer synchronized to the destination. If the service fails to be stopped, OMS provides two options: Retry and Skip.
Notice
You can choose to skip this step only after you confirm that forward synchronization has been completed in the background. Otherwise, data of the source may be unexpectedly written to the destination. Proceed with caution.
Process database objects
This step aims to process objects that are ignored during data migration or not supported by OMS. This ensures normal running of business after its cutover to the destination.
Migrate database objects to the destination: You need to migrate triggers, functions, stored procedures, and other database objects at the source that are not supported by OMS to the destination. After you complete this operation, click Mark as Complete.
Disable triggers and FOREIGN KEY constraints at the source: You need to perform this operation only in the reverse incremental migration phase of a data migration project. This aims to protect data from being affected by triggers or FOREIGN KEY constraints during reverse incremental migration. After you complete this operation, click Mark as Complete.
Supplement objects ignored during schema migration to the destination: This operation is automatically performed only when the destination is an Oracle database, an Oracle tenant of OceanBase Database, or a DB2 LUW database. This operation aims to supplement CHECK constraints, FOREIGN KEY constraints, and other objects ignored during schema migration to the destination. When the type of the destination is not any of the aforementioned ones, the preceding objects are migrated during schema migration by default and no extra operation is required.
Drop additional hidden columns and unique indexes added by OMS: This operation is automatically performed only for data migration between an Oracle database and an OceanBase database or between OceanBase databases. This operation aims to drop the additional hidden columns and unique indexes added at the destination by OMS to ensure data consistency during data migration. The execution time of this operation is subject to the data amount at the destination. OMS provides the Skip option for this operation. If you choose to skip this operation, you need to manually perform the drop operation. Proceed with caution. For more information, see Hidden column mechanisms.
Start reverse incremental migration
Note
This step is displayed only when a data migration project has the reverse incremental migration phase.
This step aims to start the incremental synchronization service for the destination to synchronize the incremental DML or DDL changes at the destination to the source. The configurations for incremental synchronization are consistent with those specified during project creation. For more information about the incremental DDL synchronization feature, see the topic of the specific database under Supported DDL operations and limits for synchronization.
Reverse incremental migration
For a Running data migration project, you can view its latency, current timestamp, and reverse incremental migration performance in the reverse incremental migration section. The latency is displayed in the following format: X seconds (updated Y seconds ago). Normally, Y is less than 20.
For a Paused or Failed data migration project, you can enable the DDL/DML statistics feature to collect statistics on the database operations performed after this feature is enabled. You can also view the specific information about the objects and performance of reverse incremental data synchronization.
The Synchronization Object Statistics tab displays the statistics about table-level DML statements executed for each incremental synchronization object in the current project. The numbers displayed in the Change Sum, Delete, Insert, and Update fields in the section above the Synchronization Object Statistics tab are the sums of the corresponding columns on this tab.
The Reverse Incremental Migration Performance tab displays the following content:
Latency: the latency in synchronizing incremental data from the destination database to the source database, in seconds.
Migration traffic: the traffic throughput of incremental data synchronization from the destination to the source, in KB/s.
Average execution time: the average execution time per SQL statement, measured in milliseconds.
Average commit time: the average commit time per transaction, measured in milliseconds.
RPS: the number of records processed per second.