Azure SQL Database (PAAS and IAAS)

Azure Learning #4 Data Sync configuration fails with error “Failed to update database 'xxxxx' because the database is read-only”

Kruti D Mehta — Wed, 04 Oct 2017 09:38:09 GMT

Recently I came across a customer who encountered the following error when configuring Azure Data Sync .

Database re-provisioning failed with the exception 'SqlException Error Code: -2146232060 - SqlError Number:3906, Message: Failed to update database 'xxxxx' because the database is read-only. SqlError Number:2759, Message: CREATE SCHEMA failed due to previous errors. For more information, provide tracing ID '#########' to customer support.'

To give some background, the customer was setting up sync between an Azure SQL Database and an on-premise SQL 2014 database

This error was encountered after due completion of Step 1 -> Creating a Sync Group , Step 2-> Adding Sync Members & Step 3-> Configure Sync Group as mentioned under Azure Documentation.

To illustrate please find the below screenshots from a test conducted in the lab environment.

Step 1 : Sync group created -> "TestSyncGroup"

Step 2: Sync Hub database added -> "test"

Step 3 : Hub database table being added -> "dbo.Table_1" ( Primary Key DbCol(int))

Error as seen from Sync logs under Azure Portal

One may wonder why the sync failed after the database was provisioned successfully as seen above.

Point to be noted: We have adhered to the data sync current limitations namely

We could create the group and add the database as a member. Then why did it fail?

Mystery isn't it. Well actually not, the error message is quite self-explanatory in this case.

Answer : We received the mentioned error because the hub database was a secondary database. It was a member of geo-replication configured on a different Azure SQL Server.

Geo-replication is a functionality in Azure SQL Database which allows you to create secondary read-only database in the same or different data center locations (regions).

Cause:

When you add the table members to the sync group it attempts to create internal tables, triggers and stored procedures within the Azure SQL hub database to track changes made to the Hub database. Once these objects are created they are used for Data Sync to carry out changes made on hub database to the member database. As Geo-replication ensures that the secondary database is in read mode only, Data Sync fails when attempting to create these required objects.

Hope you find this blog helpful. Do feel free to leave a feedback.

In our next blog we shall see how to resolve the error "Login failed. For more information, provide tracing ID '******' to customer support.'"

Azure Learning #3 Using Azure Database Migration Assistant

Kruti D Mehta — Sat, 29 Jul 2017 07:39:59 GMT

The purpose of writing this blog is to explain the difference in behavior when you assess a database and migrate a database using DMA With the assessment option you can select an On-Premise Source Server and Target Server to be Azure DB, SQL server on Azure VM or On-premise SQL Server With the migration option you can select an On-Premise Source Server an SQL server on Azure VM or On-premise SQL Server Step 1 : Launch the agent

Assessment Option Step 2: Enter project details

Step 3: Select options for assessment Check Database Compatibility Will check for unsupported and deprecated features which stop you from generating a bacpac and importing it to Azure Check Feature Parity Will again check unsupported or partially-supported features. The feature this utility discover may not block your migration but may create problems after you have migrated your database. Thus needing design changes or re-engineering

Step 4: Enter source connection details

The wizard will try to connect

Step 5: Select the source database

Step 6: Assessment progresses

Step 7: Understanding assessment The wizard will segregate the features to unsupported and partially unsupported sections as follows

When you select each feature it will give you details as to the impact of using the functionality and the recommendations to fix the errors

Same applies to partially supported features. Its important to note that the wizard will not implement the recommendation scripts for you. Rather you need to evaluate the same and modify your database accordingly to make the database compatible. Final screen

Migration Option Step 2: Enter the project details

Step 3: Select the source and target server details

If the details are entered incorrectly you will receive the below notification

Click on the "Read More" button to validate and fix the connection errors

You will keep running into error if you haven't configured the following for the SQL server instance on Azure VM

DNS name for the Azure VM
Not enabled SQL server configuration via portal
Not enabled connection on TCP port 1433 locally within the VM
Ensure you have following link https://docs.microsoft.com/en-us/azure/virtual-machines/windows/sql/virtual-machines-windows-sql-connect accurately to allow connections from DMA to your SQL instance on Azure VM
You may opt to uncheck the Encrypt connection and Trust server certificate option when connecting to the SQL Server on Azure VM

Step 4: Establish connection via DMA wizard as follows

Step 5: Select the database which you wish to migrate

Ensure you have a shared location between the source and target servers for the backup operation Step 6: Select the logins which you wish to migrate

Step 7: Start migration by selecting the button provided in the right bottom corner

Step 8: Validate migration & fix the errors

Just like performing assessment if you run into errors you will get the below screen

Select each error log for further information as to why the migration would fail and fix the errors

That's all for this blog for today folks. Hope this has given you start as to how to use this utility and get started.

Azure Learning #2 Using Azure Data Warehouse Migration Utility

Kruti D Mehta — Sat, 29 Jul 2017 06:18:31 GMT

The purpose of writing this blog is to get you familiarized with the very benefits of Azure Datawarehouse Utility which is still a preview feature. The utility can be downloaded at the below link https://docs.microsoft.com/en-us/azure/sql-data-warehouse/sql-data-warehouse-migrate-migration-utility Once you have installed the utility you will find the below shortcut created on your desktop Root path : C:\Program Files (x86)\Data Warehouse Migration Utility Step 1: Enter the source and destination The utility allows you to select from either of the below sources For the purpose of this blog we shall be using Azure SQL Database. Step 2 : Enter the credentials to connect to the Azure SQL Database -> source Step3 : Select the database which you wish to migrate Step 4: Select the objects you wish to migrate from the database Step 5A: Migrating Schema When you select migrating schema you are navigated to the scripts page as follows You can either run the script where you will be prompted to enter the destination server credentials or save the script in the form of .sql file Step 5B : Migrating Data When you select migrate data option you are directed to the following page A package gets created as follows You are prompted to enter the destination details as follows If all the details are enter correctly the wizard completes as follows Step 6: Running .bat file A windows batch file is created at the location mentioned as follows Upon execution of the above file the below screen flashes

Azure Learning #1 Connectivity errors from External Network to Azure database

Kruti D Mehta — Sat, 29 Jul 2017 06:13:28 GMT

This blogs aims at troubleshooting connectivity errors observed when trying to connect via SSMS or other client drivers from your corporate network or public network to azure database. You may find similar blogs however this blogs collates all the information available for such issues. We as engineers often come across scenarios where customer's have tried to troubleshoot a few scenarios and were successful in resolving the errors but there is an ambiguity in understanding the cause. The sole purpose of this article is to provide better understanding co-relating the root cause direct at pre-requites when connecting to Azure database. Pre-requisites for connecting to Azure databases.

Dedicated IP address -> By default Azure SQL server is designed to prevent any connections until you specify which IP address has permission to connect. The firewall grants access to databases based on the originating IP address of each computer/resource.
Outgoing TCP 1433 enabled -> On the computer that hosts your client program, ensure the firewall allows outgoing TCP communication on port 1433.

Possible causes of connection failures to Azure Database.

IP address blocked by Azure Firewall
Outbound connections blocked from client machine
Network reconfiguration on the client side: for example, a new IP address or a proxy server.
Bad connection string (username and/or password and/or server-name)
Faulty drivers or providers

Note: Driver is a program installed on a workstation or a server; it allows programs to interact with a Database Management System (DBMS). Such as, JDBC driver provides database connectivity through the standard JDBC application program interface (APIs) available in J2EE. A data provider is a set of libraries that is used to communicate with data source. Such as, SQL data provider for SQL, Oracle data provider for Oracle, OLE DB data provider for access, excel and MySQL. It serves as a bridge between an application and a data source and is used to retrieve data from a data source and to reconcile changes to that data back to the data source. Identifying the cause of failure Outbound traffic not allowed from client to access Azure database Test 1: ping .database.windows.net In the above example server-name australiaeast1-a.control.database.windows.net resolves to IP address [191.238.66.109]. Thus if there is a problem with the ISP or internal network the name will not resolve. Test 2 : tracert .database.windows.net Tracert is used to track the number of hops and IP address at which the packet drop. In the above example at HOP-7 we get the location ae17-0.sge-96cbe-1a.ntwk.msn.net [104.44.224.215]. The IP address will be within the range of Windows Azure Datacenter IP Ranges list. Location xxxxxx.ntwk.msn.net indicates that the connection was not dropped internally and reached Azure cloud. However should the underlying cause be internal network related your request would not reach the location xxxxx.ntwk.msn.net Frequent error message due to this cause: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 0 - Access is denied.) (Microsoft SQL Server, Error: 5) Outbound TCP traffic blocked on port 1433 Should the above test succeed and you still are not able to connect to the Azure database you need to test the TCP port 1433. Test 3:Telnet .database.windows.net 1433 If telnet is not enabled you will get the below error Enable telnet client from your host machine

Click Start > Control Panel.
Click Programs and Features.
Click Turn Windows features on or off.
In the Windows Features dialog box, check the Telnet Client check box.
Click OK. The system installs the appropriate files. This will take a few seconds to a minute.

One enabled fire the below command

Should the entry be successful you will get the below message Connecting To australiaeast.database.windows.net... Followed by a blank screen

Problem with the provider Test 4: Test UDL Connection

Create a file TestConn.udl on your desktop. Once created it shows up in the below icon form.

(Note: Should you not get the above icon change your folder options as follows

Click Start > Control Panel -> File Explorer Options

View Tab -> Uncheck "Hide extensions for know file types" options -> OK)

One the file is created and you double click you will be taken to "Connection" tab.
Ensure the Timeout is 30 seconds under Advanced Tab.
Test the connection under Connection Tab