Overview

This topic describes how to use DTS to check the connectivity of the source database during PreCheck.

 

Description

To ensure successful data migration, you must check whether DTS servers can connect to the source database during PreCheck. The following describes causes of source database connectivity check failures and corresponding troubleshooting methods. If the source database connectivity PreCheck fails, the possible causes are as follows:

 

The database account or password is incorrect.

Detection method

Get a device that can connect to the source database. On the device, enter the database account and password that are specified in the data migration task to check whether the account or password is correct.

Note: You can also check the account and password on the server where the source database resides.

 

Solution 

Login DTS console, modify the data migration task, enter the correct database account and database password, and re-run the PreCheck.

 

SOURCE database restricts source IP addresses.

Detection method

  1. You can enter the database account and password specified in the data migration task on the server where the source database resides and connect to the database. If the connection is successful, it indicates that the source database disallows the access from the IP address.
  2. If the source database is a MySQL database, you can use a MySQL client to connect to the database and run the following SQL statement for inspection:
    SELECT HOST FROM mysql.user WHERE user='[$UserName]',password='[$PassWord]';
    Note:
  3. If the source database is an SQL Server database, check whether a firewall is set up on the Server where SQL Server is installed, or whether the endpoint or triggers in the source database restrict the access from the source IP address.
  4. If the source database is an Oracle database, check the configuration file of the source database. sqlnet.ora, confirm configuration items TCP.VALIDNODE_CHECKING is it yes. If yes indicates that the source database disallows the access from the source IP address.

 

Solution

  1. If the source database is a MySQL database, run the following SQL statement to authorize the database account.
    GRANT ALL ON *.* * TO '[$UserName]'@'%' IDENTIFIED BY '[$PassWord]';
  2. If the source database is an SQL Server database, disable the firewall or triggers.
  3. If the source database is an Oracle database, set the TCP.VALIDNODE_CHECKING item to no and restart the process.
  4. After performing the above repair operation, log in DTS console, and re-execute the pre-check.

 

A firewall is configured for the server where the source database resides

Detection method

  1. If the server where the source database resides runs a Windows system, find Windows Firewall from the control panel to check whether a firewall is configured for the server.
  2. If the server where the source database resides runs Linux, connect to the server by using a Shell tool. iptables -L command to check whether the server is configured with a firewall.

 

Solution

After the firewall is disabled, log on. DTS console, and re-execute the pre-check.

 

Network connections fail

If the connectivity check still fails after the troubleshooting, the network between DTS servers and the source database may be unavailable. You can submit a ticket to contact Alibaba Cloud technical support personnel.

 

Application scope

  • Data Transmission Service (DTS)