tutorial-replicating-data-between-continuously-connected-servers.md

title	Tutorial: Configure Replication between Two Fully Connected Servers (Transactional) | Microsoft Docs
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Tutorial: Configure Replication between Two Fully Connected Servers (Transactional)

[!INCLUDEappliesto-ss-xxxx-xxxx-xxx-md] Transactional Replication is a good solution to the problem of moving data between continuously connected servers. Using the Replication Wizard, you can easily configure and administer a replication topology. This tutorial shows you how to configure a Transactional Replication topology for continuously connected servers. For more information about how Transactional Replication works, please see Transactional Replication Overview.

What You Will Learn

This tutorial will show you how to publish data from one database to another using transactional replication.

In this tutorial, you will learn how to:

[!div class="checklist"]

• Create a publisher via Transactional Replication
• Create a subscriber for the Transactional publisher
• Validate the Subscription and measure latency
• Troubleshooting Replication Error Methodology

Prerequisites

This tutorial is intended for users who are familiar with basic database operations, but who have limited experience with replication. This tutorial requires that you have completed the previous tutorial, Preparing the Server for Replication.

To use this Tutorial, your system must have SQL Server Management Studio (SSMS) and these components:

• At the Publisher server (source):

  • Any edition of [!INCLUDEssNoVersion], except SQL Server Express or SQL Compact. These editions cannot be replication Publishers.
  • [!INCLUDEssSampleDBUserInputNonLocal] sample database. To enhance security, the sample databases are not installed by default.

• Subscriber server (destination):

  • Any edition of [!INCLUDEssNoVersion], except [!INCLUDEssEW]. [!INCLUDEssEW] cannot be a Subscriber in transactional replication.

• Install SQL Server Management Studio.

• Install SQL Server 2017 Developer Edition.

• Download an AdventureWorks Sample Databases. For instructions on restoring a database in SSMS, please see Restoring a Database.

Note

• Replication is not supported on SQL Servers that are more than two versions apart. For more information, please see Supported SQL Versions in Repl Topology.
• In [!INCLUDEssManStudioFull], you must connect to the Publisher and Subscriber using a login that is a member of the sysadmin fixed server role. For more information on the sysadmin role, please see Server Level Roles.

Estimated time to complete this tutorial: 60 minutes.

Configure the Publisher for Transactional Replication

In this section, you will create a transactional publication using [!INCLUDEssManStudioFull] to publish a filtered subset of the Product table in the [!INCLUDEssSampleDBobject] sample database. You will also add the SQL Server login used by the Distribution Agent to the publication access list (PAL). Before starting this tutorial, you should have completed the previous tutorial, Preparing the Server for Replication.

Create a publication and define articles

1. Connect to the Publisher in [!INCLUDEssManStudioFull], and then expand the server node.

2. Right-click the SQL Server Agent and select Start. The SQL Server Agent should be running before you create the publication. If this does not start your agent, you'll need to do so manually from the SQL Server Configuration Manager.

3. Expand the Replication folder, right-click the Local Publications folder, and select New Publication. This will launch the Publication Configuration Wizard:

   

4. On the Publication Database page, select [!INCLUDEssSampleDBobject], and then select Next.

5. On the Publication Type page, select Transactional publication, and then select Next:

   

6. On the Articles page, expand the Tables node, select the Product check box. Then expand Product and clear the checkboxes next to ListPrice and StandardCost. Select Next:

   

7. On the Filter Table Rows page, select Add.

8. In the Add Filter dialog box, select the SafetyStockLevel column, select the right arrow to add the column to the Filter statement WHERE clause of the filter query. Then manually type in the WHERE clause modifier as follows:

   WHERE [SafetyStockLevel] < 500  

   

9. Select OK, and then select Next.

10. Select the Create a snapshot immediately and keep the snapshot available to initialize subscriptions check box, and select Next:

    

11. On the Agent Security page, clear Use the security settings from the Snapshot Agent check box.

    a. Select Security Settings for the Snapshot Agent, enter <Publisher_Machine_Name>\repl_snapshot in the Process account box, supply the password for this account, and then select OK:

    

12. Repeat the previous step to set <Publisher_Machine_Name>\repl_logreader as the process account for the Log Reader Agent, and then select OK:

    

13. On the Complete the Wizard page, type AdvWorksProductTrans in the Publication name box, and select Finish:

    

14. After the publication is created, select Close to complete the wizard.

    You may encounter the following error if your SQL Server Agent is not running when you attempt to create the publication. This is an indication that your publication was created successfully, but your Snapshot Agent was unable to start. If this happens, you'll need to start the SQL Server Agent, and then manually start the Snapshot Agent. Instructions for this are covered in the next section:

    

To view the status of snapshot generation

1. Connect to the Publisher in [!INCLUDEssManStudioFull], expand the server node, and then expand the Replication folder.

2. In the Local Publications folder, right-click AdvWorksProductTrans, and then select View Snapshot Agent Status:

   

3. The current status of the Snapshot Agent job for the publication is displayed. Verify that the snapshot job has succeeded before you continue to the next section.

   If your SQL Server Agent was not running when you first created the publication, you'll see that the Snapshot Agent was 'never run' when you check the Snapshot Agent Status for your publication. If that's the case, select Start to start your Snapshot Agent:

   

   If you see an error here, please see Troubleshoot Errors with Snapshot Agent.

To add the Distribution Agent login to the PAL

1. Connect to the Publisher in [!INCLUDEssManStudioFull], expand the server node, and then expand the Replication folder.

2. In the Local Publications folder, right-click AdvWorksProductTrans, and then select Properties. The Publication Properties dialog box is displayed.

   a. Select the Publication Access List page, and select Add.
   b. In the Add Publication Access dialog box, select <Publisher_Machine_Name>\repl_distribution and select OK. Select OK:

See Also:
Replication Programming Concepts

Create a subscription to the Transactional publication

In this section, you will add a subscriber to the Publication that was previously created. This tutorial uses a remote subscriber (NODE2\SQL2016) but a subscription can also be added locally to the publisher.

To create the subscription

1. Connect to the Publisher in [!INCLUDEssManStudioFull], expand the server node, and then expand the Replication folder.

2. In the Local Publications folder, right-click the AdvWorksProductTrans publication, and then select New Subscriptions. The New Subscription Wizard launches:

   

3. On the Publication page, select AdvWorksProductTrans, and then select Next:

   

4. On the Distribution Agent Location page, select Run all agents at the Distributor, and then select Next. For more information on pull and push subscriptions, please see Subscribe to Publications:

   

5. On the Subscribers page, if the name of the Subscriber instance is not displayed, select Add Subscriber and then select Add SQL Server Subscriber from the drop-down. This will launch the Connect to Server dialog box. Enter the Subscriber instance name and then select Connect.

   a. Once the Subscriber has been added, check the box next to the instance name of your Subscriber. Then select New Database under Subscription Database:

7. This will launch the New Database dialog box. Enter ProductReplica in the Database name box, select OK, and then select Next:

   

8. In the Distribution Agent Security dialog box, select the ellipsis (…) button. Enter <Publisher_Machine_Name>\repl_distribution in the Process account box, enter the password for this account, select OK, and then select Next:

   

9. Select Finish to accept the default values on the remaining pages and complete the wizard.

Setting database permissions at the Subscriber

1. Connect to the Subscriber in [!INCLUDEssManStudioFull], expand Security, right-click Logins, and then select New Login.

   a. On the General page, under Login Name select Search and add the login for <Subscriber_Machine_Name>\repl_distribution. b. On the User Mappings page, grant the login db_owner for the ProductReplica database:

   

2. Select OK to close the New Login dialog box.

To view the synchronization status of the subscription

1. Connect to the Publisher in [!INCLUDEssManStudioFull], expand the server node, and then expand the Replication folder.

2. In the Local Publications folder, expand the AdvWorksProductTrans publication, right-click the subscription in the ProductReplica database, and then select View Synchronization Status. The current synchronization status of the subscription is displayed:
   

3. If the subscription is not visible under AdvWorksProductTrans, press F5 to refresh the list.

See Also:
Initialize a Subscription with a Snapshot
Create a Push Subscription
Subscribe to Publications

Measuring Replication Latency

In this section, you will use tracer tokens to verify that changes are being replicated to the Subscriber and to determine latency. Latency is the time it takes for a change made at the Publisher to appear to the Subscriber.

1. Connect to the Publisher in [!INCLUDEssManStudioFull], expand the server node, right-click the Replication folder, and then select Launch Replication Monitor:

   

2. Expand a Publisher group in the left pane, expand the Publisher instance, and then select the AdvWorksProductTrans publication.

   a. Select the Tracer Tokens tab.
   b. Select Insert Tracer.
   c. View elapsed time for the tracer token in the following columns: Publisher to Distributor, Distributor to Subscriber, Total Latency. A value of Pending indicates that the token has not reached a given point:

   

See Also
Measure Latency and Validate Connections for Transactional Replication

Troubleshooting Replication Error Methodology

This section teaches you how to troubleshoot basic replication synchronization failures. Please note that this section is meant to introduce you to navigating the replication components with the aim of troubleshooting. However, the actual errors that you encounter may be different than what is discussed here, and as such may need a different resolution. If that is the case, further troubleshooting is necessary and is outside the scope of this tutorial.

Troubleshoot Errors with Snapshot Agent

The Snapshot Agent is the agent that generates the snapshot, and writes it to the specified snapshot folder.

1. To view the status of your snapshot agent, expand the Local Publication node under replication, right select your publication AdvWorksProductTrans > View Snapshot Agent Status.

2. If an error is reported in the Snapshot Agent Status, more details can be found in the Snapshot Agent job history. To access this, expand SQL Server Agent in Object Explorer and open the Job Activity Monitor.

   a. Sort by Category and identify the Snapshot Agent by the category 'REPL-Snapshot'.

   b. Right-click the Snapshot Agent and View History:

   

3. In the Snapshot Agent History, select the relevant error message (usually the one before the red X) and review the error message beneath the summary:

   If your windows permissions are not configured correctly for your snapshot folder, you'll see an 'access is denied' error for the Snapshot Agent. You'll need to verify permissions for the <Publisher_Machine_Name>\repl_snapshot account on your repldata folder. For more information, please see Create a share for the snapshot folder and assign permissions.

Troubleshoot Errors with Log Reader Agent

The Log Reader Agent connects to your publisher database and scans the transaction log for any transactions that are marked 'for replication'. It then adds those transactions to the Distribution database.

1. Connect to the Publisher in [!INCLUDEssManStudioFull], expand the server node, right-click the Replication folder, and then select Launch Replication Monitor:

   

   Replication Monitor launches:

2. The Red X is an indication that the publication is not synchronizing. Expand My Publishers on the left-hand side, and then expand the relevant publisher server.

3. Select the AdvWorksProductTrans publication on the left and then look for the Red X on one of the tabs to identify where the issue is. In this case, the Red X is on the Agents Tab, indicating that one of the Agents is running into an error:

   

4. Select the Agents Tab to identify which agent is encountering the error:

   

5. This view will show you two Agents, the Snapshot Agent and the Log Reader Agent. The one encountering an error will have the Red X. In this case, the Log Reader Agent is the one with the Red X, which indicates there's an issue with it. Double-click the line that's reporting the error, in this case the Log Reader Agent. This will launch the Agent History for the Agent you've selected, in this case the Log Reader Agent history. This provides more information about the error:

   

   Status: 0, code: 20011, text: 'The process could not execute 'sp_replcmds' on 'NODE1\SQL2016'.'.
   The process could not execute 'sp_replcmds' on 'NODE1\SQL2016'.
   Status: 0, code: 15517, text: 'Cannot execute as the database principal because the principal "dbo" does not exist, this type of principal cannot be impersonated, or you do not have permission.'.
   Status: 0, code: 22037, text: 'The process could not execute 'sp_replcmds' on 'NODE1\SQL2016'.'.        
   

6. The aforementioned error is typically caused because the owner of the publisher database is not set correctly. This typically happens when a database has been restored. To verify this, expand Databases in Object Explorer > right-click AdventureWorks2012 > Properties. Verify that an owner exists under the Files tab. If this field is blank, then this is the likely cause of your issue:

   

7. If the owner is blank, open a New Query Window within the context of the AdventureWorks2012 database. Run the following T-SQL code snippet:

   -- set the owner of the database to 'sa' or a specific user account, without the brackets. 
   EXEC sp_changedbowner '<useraccount>'

8. You'll need to restart the Log Reader Agent. To do this, expand the SQL Server Agent node in Object Explorer and open the Job Activity Monitor. Sort by Category and identify the Log Reader Agent by the 'REPL-LogReader' category. Right-click the Log Reader Agent job and Start Job at Step:

   

9. Validate that your publication is now synchronizing by opening the Replication Monitor again. If it's not already open, it can be found by right-clicking Replication in Object Explorer.

10. Select the AdvWorksProductTrans publication, select the Agents tab, and double-select the Log Reader Agent to open the agent history. You should now see that the Log Reader Agent is running and either replicating commands, or that it has "No Replicated Transactions":

    

Troubleshoot errors with Distribution Agent

The Distribution Agent takes data it finds in the Distribution database and then applies it to the Subscriber.

1. Connect to the Publisher in [!INCLUDEssManStudioFull], expand the server node, right-click the Replication folder, and then select Launch Replication Monitor.

2. In Replication Monitor, select the AdvWorksProductTrans publication, and select the All Subscriptions tab. Right-click the Subscription and View Details:

   

3. The Distributor to Subscriber history dialog box opens, and clarifies what error the agent is encountering:

   

    Error messages:
    Agent 'NODE1\SQL2016-AdventureWorks2012-AdvWorksProductTrans-NODE2\SQL2016-7' is retrying after an error. 89 retries attempted. See agent job history in the Jobs folder for more details.
   

4. The error indicates that the Distribution Agent is retrying. To find out more information, expand SQL Server Agent in Object Explorer > Job Activity Monitor. Sort the jobs by Category.

   a. Identify the Distribution Agent by the category 'REPL-Distribution'. Right-click the agent and View History:

   

5. Select one of the error entries and view the error text at the bottom of the window:

   

    Message:
    Unable to start execution of step 2 (reason: Error authenticating proxy NODE1\repl_distribution, system error: The user name or password is incorrect.)
   

6. This error is an indication that the password used by the Distribution Agent is incorrect. To resolve this, expand the Replication node in Object Explorer, right-click the subscription > Properties. Select the ellipses (...) next to Agent Process Account and modify the password:

   

7. Check your Replication Monitor again, which can be found by right-clicking Replication in Object Explorer. A Red X under All Subscriptions indicates that our Distribution Agent is still encountering an error. Open the Distribution to Subscriber history by right-clicking the Subscription in Replication Monitor > View Details. Here, the error is now different:

   

    Connecting to Subscriber 'NODE2\SQL2016'        
    Agent message code 20084. The process could not connect to Subscriber 'NODE2\SQL2016'.
    Number:  18456
    Message: Login failed for user 'NODE2\repl_distribution'.
   

8. This error indicates that the Distribution Agent could not connect to the subscriber, as the login failed for user NODE2\repl_distribution. To investigate further, connect to the Subscriber and open the current SQL Error Log under the Management node in Object Explorer:

   If you're seeing this error, it means that the login is missing on the subscriber. To resolve this, please see Setting database permissions at the Subscriber.

9. Once the login error has been resolved, check Replication Monitor again. If all issues have been addressed, you should see a green arrow next to the Publication Name and a status of Running under All Subscriptions. Right-click the Subscription to launch the Distributor to Subscriber history once more to verify success. If this is the first time running the distribution agent, you'll see that the snapshot has been bulk copied to the subscriber as the picture below indicates:

   

Next steps

You have successfully configured both your Publisher and your Subscriber for your Transactional Replication. You can now insert, update, or delete data in the Product table at the Publisher. Then you can query the Product table at the Subscriber to view the replicated changes. The next article will teach you how to configure Merge replication.

Advance to the next article to learn more

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