From Oracle to GaussDB Distributed

Supported Source and Destination Databases

**Table 1** Supported databases
Source DB	Destination DB
On-premises databases (Oracle 10g, 11g, 12c, 18c, 19c, and 21c) Self-built databases on ECS (Oracle 10g, 11g, 12c, 18c, 19c, and 21c)	GaussDB distributed

Suggestions

When a task is being started or in the full synchronization phase, do not perform DDL operations on the source database. Otherwise, the task may be abnormal.
To keep data consistency before and after the synchronization, ensure that no data is written to the destination database during the synchronization.

The success of database synchronization depends on environment and manual operations. To ensure a smooth synchronization, perform a synchronization trial before you start the synchronization to help you detect and resolve problems in advance.
You are advised to start your synchronization task during off-peak hours by setting Start Time to Start at a specified time. A less active database is easier to synchronize successfully. If the data is fairly static, there is less likely to be any severe performance impacts during the synchronization.
- If network bandwidth is not limited, the query rate of the source database increases by about 50 MB/s during full synchronization, and two to four CPUs are occupied.
- The data being synchronized may be locked by other transactions for a long period of time, resulting in read timeout.
- When DRS concurrently reads data from a database, it will use about 6 to 10 sessions. The impact of the connections on services must be considered.
- If you read a table, especially a large table, during the full migration, the exclusive lock on that table may be blocked.
- For more information about the impact of DRS on databases, see What Is the Impact of DRS on Source and Destination Databases?
Data-Level Comparison
To obtain accurate comparison results, compare data at a specified time point during off-peak hours. If it is needed, select Start at a specified time for Comparison Time. Due to slight time difference and continuous operations on data, data inconsistency may occur, reducing the reliability and validity of the comparison results.

Precautions

Before creating a synchronization task, read the following notes:

You are advised to create an independent database account for DRS task connection to prevent task failures caused by database account password modification.
After changing the account passwords for the source and destination databases, modify the connection information in the DRS task as soon as possible to prevent automatic retry after a task failure. Automatic retry will lock the database accounts.

**Table 2** Precautions
Type	Restrictions
Database permissions	Source database: Full synchronization requires the following permissions: CREATE SESSION, SELECT ANY DICTIONARY, and SELECT for single tables (GRANT SELECT ON <userName.tbName> to drsUser). Full+incremental synchronization and incremental synchronization: Oracle 12c or later in tenant mode: To synchronize a container database (CDB) of Oracle 12c or later, you must have the following permissions: CREATE SESSION, SELECT ANY DICTIONARY, SELECT for a single table (GRANT SELECT ON <userName.tbName> to drsUser), EXECUTE_CATALOG_ROLE, SELECT ANY TRANSACTION, and LOGMINING. To synchronize a pluggable database (PDB) of Oracle 12c or later, you must have the following permissions: CREATE SESSION, SELECT ANY DICTIONARY, SELECT for a single table (GRANT SELECT ON <userName.tbName> to drsUser), EXECUTE_CATALOG_ROLE and SELECT ANY TRANSACTION permissions for a PDB, and CREATE SESSION, SELECT ANY DICTIONARY, EXECUTE_CATALOG_ROLE, SELECT ANY TRANSACTION, LOGMINING and SET CONTAINER (GRANT SET CONTAINER TO <userName> CONTAINER=ALL) permissions for a CDB. Oracle 12c or later in non-tenant mode: You must have the following permissions: CREATE SESSION, SELECT ANY DICTIONARY, SELECT for a single table (GRANT SELECT ON <userName.tbName> to drsUser), EXECUTE_CATALOG_ROLE, SELECT ANY TRANSACTION, and LOGMINING. To synchronize a database of Oracle 11g or earlier, you must have the following permissions: CREATE SESSION, SELECT ANY DICTIONARY, SELECT for a single table (GRANT SELECT ON <userName.tbName> to drsUser), EXECUTE_CATALOG_ROLE, and SELECT ANY TRANSACTION. During incremental synchronization, enable PK, UI, or ALL supplemental logging for the source Oracle database at the database level or table level. If supplemental logging is enabled at table level, enable supplemental logging again after you rebuild or rename tables. During the synchronization, ensure that the preceding settings are always enabled. Oracle 12c or later does not support incremental synchronization using accounts whose ORACLE_MAINTAINED is Y (except system/sys), because accounts with this attribute do not have the permission to parse logs. The destination database must have the following permissions: Database-level permission: Log in to the postgres base database as user root or user DATABASE with the Sysadmin role, and grant the CREATE and CONNECT permissions to user DATABASE. Statement: GRANT CREATE, CONNECT ON DATABASE <database> TO <user> Schema-level permission: Log in to the database as user root or user DATABASE with the Sysadmin role, or the owner of the database, and grant the CREATE and USAGE permissions of the schema to the user. Statement: GRANT CREATE, USAGE ON SCHEMA <schema> TO <user> Table-level permission: Log in to the database as user root or user DATABASE with the Sysadmin role, or the owner of the database, and grant the DML permission for tables in the SCHEMA to the user. (The SELECT permission is required only for tables without primary keys.) Statement for granting the DML permission on all tables in the SCHEMA: GRANT SELECT, UPDATE, INSERT, DELETE, INDEX, ALTER ON ALL TABLES IN SCHEMA <schema> TO <user> Statement for granting the DML permission on a specified table in the SCHEMA: GRANT SELECT, UPDATE, INSERT, DELETE, INDEX, ALTER ON TABLE <schema.table> TO <user> If gs_loader is used to create system catalogs (such as public.pgxc_copy_error_log and public.gs_copy_summary) in the destination database, the all privilege permission is required for accessing the system catalogs.For details, see gs_loader.
Synchronization object	During full synchronization, tables, common indexes, primary keys, unique constraints, and data can be synchronized. Tables can be synchronized in real time during incremental synchronization. Full synchronization does not support the following column types: bfile, xmltype, sdo_geometry, urowid, and user-defined types. Incremental synchronization does not support the following column types: XMLTYPE, bfile, xmltype, sdo_geometry, urowid, interval year to month, interval day to second, and user-defined types. During the incremental synchronization, if the source database is a physical standby Oracle database, data of the LOB type cannot be parsed (the data dictionary cannot be generated). If the table to be synchronized contains data of the LOB type, the incremental synchronization will fail. In the incremental phase, Oracle extended characters are not supported. The standard character set cannot parse Oracle customized extended characters. For incremental synchronization, the LOB type supports only the BasicFiles attribute and does not support the SecureFiles attribute. The size of the LOB type must be less than 10 MB. During full synchronization, the table structure does not support bitmap indexes, inverted indexes, and function indexes. The maximum precision supported by timestamp and interval day to second is 6. During incremental synchronization, if the source or destination database is abnormal, the task fails. After the database is recovered, the task is globally started. The status of the original capture or replay component is ignored, and the replay component is started from the capture interruption point. For the TIMESTAMP WITH TIME ZONE data type, the data cannot be greater than 9999-12-31 23:59:59.999999 after being converted based on the time zone of the destination database. The default values of the source database can be to_date and sys_guid functions. To use other functions as default values, ensure that the destination database has the same functions. If the destination database does not have the corresponding function, the following results may be displayed: The default value may be left empty. The table fails to be created. As a result, the object comparison result is inconsistent or the task fails. If the table contains only LOB columns, data inconsistency may occur. If the empty function of the LOB type is used to write data in the Oracle database, the value queried through JDBC is an empty string. Whether the value is an empty string or NULL after being written to the destination database depends on the processing of the empty string in the destination database. For a table that does not have a primary key or index, the number of columns of non-large fields must be greater than 3. Otherwise, incremental synchronization may fail because all columns cannot be matched. Tables whose default values contain expressions of functions cannot be synchronized. Temporary tables in the source database cannot be synchronized. Tables with virtual columns in the source database cannot be synchronized. A user-defined table that has no primary key and is a partitioned table cannot be synchronized. Otherwise, the task may fail. When you manually create a table structure, the time type in the destination database must be the same as that in the source database. Otherwise, time data may be inconsistent due to time zone conversion.
Source database	Database object names, such as the database name and table name, support English characters and symbols such as #, $, and _. DRS does not support non-ASCII characters or special characters: .>`<'\,\|?!" Object names will be converted to lowercase letters after being synchronized to the destination database. To avoid synchronization failures, ensure that the selected source database tables do not contain tables with the same name but different letter cases. Only the following character sets are supported: ZHS16GBK, AL32UTF8, UTF8, US7ASCII, WE8MSWIN1252, WE8ISO8859P1, WE8ISO8859P2, WE8ISO8859P4, WE8ISO8859P5, WE8ISO8859P7, WE8ISO8859P9, WE8ISO8859P13, WE8ISO8859P15.
Destination database	The destination database must be a GaussDB distributed instance. Ensure that a database named in lowercase letters has been created in destination database. Do not use foreign keys for tables during synchronization. Otherwise, the sequence of writing data to different tables may be inconsistent with that in the source database, which may trigger foreign key constraints and cause synchronization failures. The destination table can contain more columns than the source table. However, the following failures must be avoided: Assume that extra columns on the destination cannot be null or have default values. If newly inserted data records are synchronized from the source to the destination, the extra columns will become null, which does not meet the requirements of the destination and will cause the task to fail. Assume that extra columns on the destination must be fixed at a default value and have a unique constraint. If newly inserted data records are synchronized from the source to the destination, the extra columns will contain multiple default values. That does not meet the unique constraint of the destination and will cause the task to fail.
Precautions	Cascading one-way synchronization is not supported. For example, data cannot be synchronized from instance A to instance B and then from instance B to instance C. Do not use an imprecise value type as the primary key in the database because the synchronization of UPDATE and DELETE statements in the DRS incremental scenario will be affected and value comparison will be unavailable. For details about the data types supported by the primary key, see Mapping Data Types. The size of an Oracle archive log file must be greater than the maximum size of a single data record to prevent incremental data parsing exceptions caused by cross-file (more than two log files) of a single data record. If the Oracle character set is WE8MSWIN1252 or WE8ISO8859P1, the CLOB column synchronized to the destination database may contain garbled characters. You can change the character set of the source database to AL32UTF8 before the synchronization. If the PDB database is used for synchronization, all PDBs must be enabled during incremental synchronization due to the restrictions of the Oracle LogMiner component. In Oracle 12.2 and later versions, due to the restrictions of the Oracle LogMiner component, a schema, table, or column name contains no more than 30 characters during an incremental synchronization. If the total length of the storage data in each row exceeds the upper limit (8192 bytes by default) of GaussDB, the task may fail. For an Oracle RAC cluster, use the scan IP address and service name to create a task. The SCAN IP address can provide better fault tolerance, load capability, and synchronization experience. If the source is an Oracle RAC database and the SCAN IP address is used to configure a DRS task, ensure that the SCAN IP address and DRS node IP address can communicate with all virtual IP addresses of the source database. Otherwise, the connectivity check fails. If the SCAN IP address is not used, the virtual IP address of a node can be used. In this case, DRS logs are parsed only on the RAC node specified by the virtual IP address. If the source is an RAC database, all RAC nodes must be online when incremental synchronization is started for the first time. Otherwise, an error occurs during incremental synchronization. If the source is an RAC database, the number of nodes cannot be increased or decreased during incremental synchronization to avoid incremental synchronization exceptions and ensure strong data consistency. The table without a primary key lacks a unique identifier for rows. When the network is unstable, you may need to retry the task several times, or data inconsistency may occur. If the character sets of the source database are different from those of the destination database, adjust the field length of the destination database based on the site requirements. For example, the source character set is ZHS16GBK and the destination character set is UTF8, a Chinese character of ZHS16GBK occupies two bytes, and a Chinese character of UTF8 occupies three bytes. When CHAR or VARCHAR data type is synchronized to the destination database, the field length may exceed the defined length, so you need to increase the field length to 1.5 times of that in the source database. If you use DRS to synchronize table structures, the tables, constraints, and indexes in the same schema cannot have the same name with different letter cases. For example, table A contains an index named inx1, and table B contains an index name a. Table A and index a have the same name with different letter cases, which will cause table structure synchronization to fail. If multiple schemas are mapped to one schema, the source schemas cannot contain tables, constraints, and indexes with the same name but different letter cases. During synchronization, do not modify or delete the usernames, passwords, permissions, or ports of the source and destination databases. During the synchronization, do not perform the resetlogs operation on the source Oracle database. Otherwise, data cannot be synchronized and tasks cannot be restored. During synchronization, the rollback operation of the LOB type is not supported. Otherwise, the synchronization task fails. During the synchronization, the username (schema name) of the source Oracle database cannot be changed, including the scenarios where the schema name is changed by modifying the USER$ dictionary table in versions earlier than 11.2.0.2 and by using ALTER USER username RENAME TO new_username in versions later than 11.2.0.2. Do not write data to the destination database table during full synchronization. Otherwise, data will be inconsistent. Full synchronization consists of two phases: table structure synchronization (including indexes) and real-time synchronization. If the structure of a table is created in the destination database, real-time synchronization starts. If a table fails to be synchronized, you can restart the task to synchronize the table data. However, the table structure is not synchronized, so you must manually create the table in the destination database. In a full synchronization for the table structure, the length of the char and varchar2 characters in the source database is automatically increased by at least 1.5 times by byte in the destination database (because the length of the destination database is in the unit of byte). The increase multiple depends on the character set of the source and destination databases. For example, if the character set is UTF8, increase the length (byte) by three times by default. If the character set is GBK, increase the length (byte) by two times by default. During table structure synchronization in a full synchronization, if the destination database has a constraint with the same name as the source database, the table fails to be created. During table structure synchronization in a full synchronization, the column name cannot be CTID, XMIN, CMIN, XMAX, CMAX, TABLEOID, XC_NODE_ID, TID, OID, GS_TUPLE_UID or TABLEBUCKETID. Otherwise, the table fails to be created. During full synchronization of the partitioned table structure, the table is converted to a non-partitioned table. During incremental synchronization, operations related to the partitioned table in the source database may fail to be executed in the destination database. When a table structure is fully synchronized, only default value constraints of the character string or number type are supported. Default value constraints of the function and sequence types are not supported. During an incremental synchronization, 0x00 at the end of BLOB and the spaces at the end of CLOB are truncated. During incremental synchronization, you are not advised to select a hybrid partition table because DML logs are not generated when data in the external partition of the hybrid partition table changes. DRS cannot obtain the changes during incremental synchronization, which may cause data inconsistency. During incremental synchronization, the incremental parsing supports only data within the valid range of the Oracle time type. Data beyond the valid range may cause task exceptions. For example, data truncation occurs if the year value is greater than 9999. In a full+incremental or incremental synchronization, the PDB database cannot be directly connected. You need to provide the service name/SID, username, and password of the CDB. During incremental synchronization, some DDL operations are supported. DDL conversion of heterogeneous databases requires semantic analysis and syntax compatibility. Only some DDL operations can be synchronized when the conversion is successful and the following conditions are met. If the conversion or execution fails, the error will be ignored. You need to manually execute the corresponding DDLs in the destination database. Table-level synchronization supports alter table add column, alter table drop column, alter table rename column, alter table modify column, and truncate table. The modification of default values is not supported. The character length of new fields in incremental DDLs is not automatically extended. During incremental synchronization, modify the start point of a capture task to resynchronize data. After the capture point is modified, the previous object-level comparison result is not displayed. If the start point of a capture task is changed separately, the change is synchronized to the start point of the replay task. That is, the start point of the replay task is the same as that of the capture task. This does not affect the change of the start point of the replay task. Full and incremental synchronization does not support hidden columns (UNUSED, INVISIBLE). If the destination database is a GaussDB distributed database, the update operation performed on the source distribution column will fail to be synchronized to the GaussDB database during incremental synchronization, causing data inconsistency. Therefore, avoid updating the distribution column. You are advised to disable the global secondary index (GSI) function for the destination database. Otherwise, incremental synchronization may fail. When editing the task to add a new table, ensure that transactions of the new table have been committed. Otherwise, transactions that are not committed may fail to be synchronized to the destination database. You are advised to add tables during off-peak hours. You are not advised to use the LOB type and extended character type (the length exceeds 4000 bytes) as incremental data filtering conditions. Oracle logs may not record the old value of update. If the synchronization table in the destination database has been associated with a sequence when the task stops, DRS automatically resets the sequence value of the destination database. The auto-increment sequence value is the source database sequence value plus the security margin, and the auto-decrement sequence value is the source database sequence value minus the security margin. The default security margin is 10,000.

Procedure

On the Data Synchronization Management page, click Create Synchronization Task.

On the Create Synchronization Instance page, select a region and project, specify the task name, description, and the synchronization instance details, and click Create Now.

Task information description

Figure 1 Synchronization task information

**Table 3** Task information
Parameter	Description
Region	The region where the replication instance is deployed. You can change the region.
Project	The project corresponds to the current region and can be changed.
Task Name	The task name must start with a letter and consist of 4 to 50 characters. It can contain only letters, digits, hyphens (-), and underscores (_).
Description	The description consists of a maximum of 256 characters and cannot contain special characters !=<>'&"\

Synchronization instance details

Figure 2 Synchronization instance details

**Table 4** Synchronization instance settings
Parameter	Description
Data Flow	Select To the cloud.
Source DB Engine	Select Oracle.
Destination DB Engine	Select GaussDB Distributed.
Network Type	Public network is used as an example. Available options: VPC, Public network and VPN or Direct Connect VPC is suitable for data synchronization between cloud databases of the same account in the same region. Public network is suitable for data synchronization from on-premises or external cloud databases to the destination databases bound with an EIP. VPN or Direct Connect is suitable for synchronization of data between on-premises databases and cloud databases, between cloud databases of different accounts in the same region, or between cloud databases across regions.
Destination DB Instance	The GaussDB distributed instance you created.
Synchronization Instance Subnet	Select the subnet where the synchronization instance is located. You can also click View Subnet to go to the network console to view the subnet where the instance resides. By default, the DRS instance and the destination DB instance are in the same subnet. You need to select the subnet where the DRS instance resides, and there are available IP addresses for the subnet. To ensure that the synchronization instance is successfully created, only subnets with DHCP enabled are displayed.
Synchronization Mode	The synchronization mode supported by a DRS task. Full+Incremental is used as an example. For details about the underlying working principles for full or incremental synchronization, see Product Architecture and Function Principles.

Task type

Figure 3 Task type

**Table 5** Task type information
Parameter	Description
Specifications	DRS instance specifications. Different specifications have different performance upper limits. For details, see Real-Time Synchronization. NOTE: DRS allows you to upgrade specifications only for single-AZ synchronization tasks. Task specifications cannot be downgraded. For details, see Changing Specifications.
AZ	Select the AZ where you want to create the DRS task. Selecting the one housing the source or destination database can provide better performance.

Enterprise Project and Tags

Figure 4 Enterprise projects and tags

**Table 6** Enterprise Project and Tags
Parameter	Description
Enterprise Project	An enterprise project you would like to use to centrally manage your cloud resources and members. Select an enterprise project from the drop-down list. The default project is default. For more information about enterprise project, see Enterprise Management User Guide. To customize an enterprise project, click Enterprise in the upper right corner of the console. The Enterprise Project Management Service page is displayed. For details, see Creating an Enterprise Project in Enterprise Management User Guide.
Tags	Tags a task. This configuration is optional. Adding tags helps you better identify and manage your tasks. Each task can have up to 20 tags. If your organization has configured tag policies for DRS, add tags to tasks based on the policies. If a tag does not comply with the policies, task creation may fail. Contact your organization administrator to learn more about tag policies. After a task is created, you can view its tag details on the Tags tab. For details, see Tag Management.

If a task fails to be created, DRS retains the task for three days by default. After three days, the task automatically stops.

On the Configure Source and Destination Databases page, specify source and destination database information and click Test Connection for both the source and destination databases to check whether they have been connected to the synchronization instance. After the connection tests are successful, click Next.

Figure 5 Source database information

**Table 7** Source database settings
Parameter	Description
IP Address or Domain Name	The IP address or domain name of the source database. NOTE: For a RAC cluster, use a Scan IP address to improve access performance.
Port	The port of the source database. Range: 1 – 65535
Database Service Name	Enter a database service name (Service Name/SID). The client can connect to the Oracle database through the database service name. For details about how to query the database service name, see the prompt on the GUI.
PDB Name	Container database (CDB) and pluggable database (PDB) are new features in Oracle 12c and later versions. This function is optional, but it must be enabled if you want to migrate only PDB tables. Enter the service name, SID, username, and password of the CDB that contains the PDB tables to be migrated.
Database Username	The username for accessing the source database.
Database Password	The password for the database username.
SSL Connection	SSL encrypts the connections between the source and destination databases. If SSL is enabled, upload the SSL CA root certificate. NOTE: The maximum size of a single certificate file that can be uploaded is 500 KB. If SSL is disabled, your data may be at risk.

Figure 6 Destination database information

**Table 8** Destination database settings
Parameter	Description
DB Instance Name	The GaussDB distributed DB instance selected during synchronization task creation. This parameter cannot be changed.
Database Username	The username for accessing the destination database.
Database Password	The password for the database username. The database username and password are encrypted and stored in the system and will be cleared after the task is deleted.

On the Set Synchronization Task page, select the synchronization object, enter the name of the destination database, and click Next.

Figure 7 Synchronization mode

**Table 9** Synchronization Object
Parameter	Description
Flow Control	You can choose whether to control the flow. Flow Control takes effect in the full phase only. Yes You can customize the maximum synchronization speed. In addition, you can set the time range based on your service requirements. The traffic rate setting usually includes setting of a rate limiting time period and a traffic rate value. Flow can be controlled all day or during specific time ranges. The default value is All day. A maximum of three time ranges can be set, and they cannot overlap. The flow rate must be set based on the service scenario and cannot exceed 9,999 MB/s. Figure 8 Flow control No The synchronization speed is not limited and the outbound bandwidth of the source database is maximally used, which will increase the read burden on the source database. For example, if the outbound bandwidth of the source database is 100 MB/s and 80% bandwidth is used, the I/O consumption on the source database is 80 MB/s. NOTE: The flow control mode takes effect only in the full synchronization phase. You can also change the flow control mode after creating a task. For details, see Modifying the Flow Control Mode.
Synchronize DDLs	DDL type for incremental synchronization. You can select Default or Custom based on your service requirements. Default During table-level synchronization, only DDLs of the selected tables will be synchronized to the destination. The supported DDL statements are CREATE_TABLE, ALTER_TABLE, and TRUNCATE_TABLE. Custom: You can select the DDL type to be synchronized as required. The DDL types supported by different data flow types are displayed on the GUI.
Synchronization Object	The left pane displays the source database objects, and the right pane displays the selected objects. You can select Tables or Import object file for Synchronization Object as required. If the synchronization objects in source and destination databases have different names, you can map the source object name to the destination one. For details, see Mapping Object Names. For details about how to import an object file, see Importing Synchronization Objects. NOTE: To quickly select the desired database objects, you can use the search function. If there are changes made to the source databases or objects, click in the upper right corner to update the objects to be synchronized. If the object name contains spaces, the spaces before and after the object name are not displayed. If there are multiple spaces between the object name and the object name, only one space is displayed. The name of the selected synchronization object cannot contain spaces.

On the Process Data page, set the filtering rules for data processing.
- If data processing is not required, click Next.
- If you need process columns or filter out data, set the corresponding rules by referring to Processing Data.
Figure 9 Processing data
On the Check Task page, check the synchronization task.
- If any check fails, review the cause and rectify the fault. After the fault is rectified, click Check Again.
  For details about how to handle check failures, see Solutions to Failed Check Items in Data Replication Service User Guide.
- If all check items are successful, click Next.
  Figure 10 Pre-check
  
  You can proceed to the next step only when all checks are successful. If there are any items that require confirmation, view and confirm the details first before proceeding to the next step.

On the displayed page, specify Start Time, Send Notifications, SMN Topic, Delay Threshold (s), and Stop Abnormal Tasks After, confirm that the configured information is correct, select the check box before the agreement, and click Submit to submit the task.

Figure 11 Task startup settings

**Table 10** Task startup settings
Parameter	Description
Start Time	Set Start Time to Start upon task creation or Start at a specified time based on site requirements. NOTE: After a synchronization task is started, the performance of the source and destination databases may be affected. You are advised to start a synchronization task during off-peak hours.
Send Notifications	This parameter is optional. After enabled, select a SMN topic. If the status, latency metric, or data of the synchronization task is abnormal, DRS will send a notification.
SMN Topic	This parameter is available only after you enable Send Notifications and create a topic on the SMN console and add a subscriber. For details, see Simple Message Notification User Guide.
Delay Threshold (s)	During an incremental synchronization, a synchronization delay indicates a time difference (in seconds) of synchronization between the source and destination database. If the synchronization delay exceeds the threshold you specify, DRS will send alarms to the specified recipients. The value ranges from 0 to 3,600. To avoid repeated alarms caused by the fluctuation of delay, an alarm is sent only after the delay has exceeded the threshold for six minutes. NOTE: If the delay threshold is set to 0, no notifications will be sent to the recipient. In the early stages of an incremental synchronization, the synchronization delay is long because a large quantity of data is awaiting synchronization. In this case, no notifications will be sent. Before setting the delay threshold, enable Send Notifications.
Data Exception Notification	This parameter is optional. After enabled, DRS will send a notification if the task data is abnormal.
Stop Abnormal Tasks After	Number of days after which an abnormal task is automatically stopped. The value must range from 14 to 100. The default value is 14. NOTE: You can set this parameter only for pay-per-use tasks. Tasks in the abnormal state are still charged. If tasks remain in the abnormal state for a long time, they cannot be resumed. Abnormal tasks run longer than the period you set (unit: day) will automatically stop to avoid unnecessary fees.

After the task is submitted, you can view and manage it on the Data Synchronization Management page.
- You can view the task status. For more information about task status, see Task Statuses.
- You can click in the upper right corner to view the latest task status.
- By default, DRS retains a task in the Configuration state for three days. After three days, DRS automatically deletes background resources, but the task status remains unchanged. When you configure the task again, DRS applies for resources for the task again. In this case, the IP address of the DRS instance changes.