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. By 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, see the 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.
• Troubleshoot errors.

Prerequisites

This tutorial is 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, make sure that your system has these products and components:

• At the publisher server (source), install:

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

• At the subscriber server (destination), install any edition of [!INCLUDEssNoVersion], except [!INCLUDEssEW]. [!INCLUDEssEW] cannot be a subscriber in transactional replication.

• Install SQL Server Management Studio (SSMS).

• Install SQL Server 2017 Developer edition.

• Download an AdventureWorks sample database. For instructions on restoring a database in SSMS, see Restoring a database.

Note

• Replication is not supported on SQL Server instances that are more than two versions apart. For more information, see Supported SQL Server Versions in Replication Topology.
• In [!INCLUDEssManStudioFull], you must connect to the publisher and subscriber by using a login that is a member of the sysadmin fixed server role. For more information on this role, see Server-level roles.

Estimated time to complete this tutorial: 60 minutes

Configure the publisher for transactional replication

In this section, you create a transactional publication by using [!INCLUDEssManStudioFull] to publish a filtered subset of the Product table in the [!INCLUDEssSampleDBobject] sample database. You also add the SQL Server login used by the Distribution Agent to the publication access list (PAL).

Create a publication and define articles

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

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

3. Expand the Replication folder, right-click the Local Publications folder, and select New Publication. This step starts the New Publication 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 and select the Product check box. Then expand Product and clear the check boxes 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 the Use the security settings from the Snapshot Agent check box.

    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. 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 might 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.

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 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, see Troubleshoot errors with the Snapshot Agent.

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 appears.

   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.

   

For more information, see Replication Programming Concepts.

Create a subscription to the transactional publication

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

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 starts:

   

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, 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 list. This step opens the Connect to Server dialog box. Enter the subscriber instance name and then select Connect.

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

   

6. The New Database dialog box appears. Enter ProductReplica in the Database name box, select OK, and then select Next:

   

7. 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:

   

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

Set 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.

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 appears:

   

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

For more information, see:
Initialize a Subscription with a Snapshot
Create a Push Subscription
Subscribe to Publications

Measure replication latency

In this section, you 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.

   

For more information, see Measure Latency and Validate Connections for Transactional Replication.

Error troubleshooting methodology

This section teaches you how to troubleshoot basic replication synchronization failures. This section introduces you to navigating the replication components with the aim of troubleshooting. However, the actual errors that you encounter might be different from what is discussed here--and might need a different resolution. If that is the case, further troubleshooting is necessary and is outside the scope of this tutorial.

Troubleshoot errors with the Snapshot Agent

The Snapshot Agent 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-click your publication AdvWorksProductTrans > View Snapshot Agent Status.

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

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

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

   

3. In the Snapshot Agent history, select the relevant log entry. This will usually be a line or two before the entry reporting the error. (Errors are indicated by the red X.) Review the message text in the text box below the logs:

   

   The replication agent had encountered an exception. 
   Exception Message: Access to path '\\node1\repldata.....' is denied.
   

   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, see Create a share for the snapshot folder and assign permissions.

Troubleshoot errors with the 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 opens:

   

2. The red X is an indication that the publication is not synchronizing. Expand My Publishers on the left 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 problem 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 shows you two agents, the Snapshot Agent and the Log Reader Agent. The one that's encountering an error will have the red X. In this case, the Log Reader Agent has the Red X.

   Double-click the line that's reporting the error--in this case, Log Reader Agent. The agent history appears for the agent that you've selected. In this case, it's the Log Reader Agent history. It 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 publication error typically happens when the owner of the publisher database is not set correctly after a database is restored. Expand Databases in Object Explorer > right-click AdventureWorks2012 > Properties. Verify that an owner exists under the Files page. If this box is blank, then this is the likely cause of your problem:

   

7. If the owner is blank on the Files page, 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>'
   -- example for sa: exec sp_changedbowner 'sa'
   -- example for user account: exec sp_changedbowner 'sqlrepro\administrator' 

8. Restart the Log Reader Agent. To do this, expand the SQL Server Agent node in Object Explorer and open 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 select Start Job at Step.

   

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

10. Select the AdvWorksProductTrans publication, select the Agents tab, and double-click 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 the Distribution Agent

The Distribution Agent finds data 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 select View Details:

   

3. The Distributor To Subscriber History tab 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 get more information, expand SQL Server Agent in Object Explorer > Job Activity Monitor. Sort the jobs by Category.

   Identify the Distribution Agent by the category REPL-Distribution. Right-click the agent and select 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 indicates that the password that the Distribution Agent used is incorrect. To resolve this, expand the Replication node in Object Explorer, right-click the subscription > Properties. Select the ellipsis (...) next to Agent Process Account and modify the password.

   

7. Check Replication Monitor again. You can find it by right-clicking Replication in Object Explorer. A red X under All Subscriptions indicates that the Distribution Agent is still encountering an error. Open the Distribution To Subscriber History tab 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, because the login failed for the user NODE2\repl_distribution. To investigate further, connect to the subscriber and open the current SQL Server error log under the Management node in Object Explorer:

   

   If you're seeing this error, the login is missing on the subscriber. To resolve this problem, see Set database permissions at the subscriber.

9. After you resolve the login error, check Replication Monitor again. If all problems have been fixed, you should see a green arrow next to the publication name and a status of Running under All Subscriptions.

   Right-click the subscription to open the Distributor To Subscriber History tab and verify success. If this is your first time running the Distribution Agent, you can see that the snapshot has been bulk copied to the subscriber:

   

Next steps

You have successfully configured both your publisher and your subscriber for 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:

[!div class="nextstepaction"] Tutorial: Configure replication between a server and mobile clients (merge)