Azure SQL Database SLA

Can you improve on the baseline (service level agreement) SLA of 99.99 % for Azure SQL Database? How can you get 99.995% as shown below, from official Microsoft documentation?

(source: https://azure.microsoft.com/en-gb/blog/understanding-and-leveraging-azure-sql-database-sla/)
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SQL Server Stretch DB to Azure

Since SQL Server 2016 we could leverage Microsoft Azure to dynamically move “cold” portions of data away from on-premises storage for longer retention time periods. Whilst in theory being a great idea the cost was a blocker for some and with a cumbersome setup process. SQL Server 2019 addresses this by making the costs of storing the data in the cloud more competitive and making the setup more streamlined with the use of the Data Migration Assistant (DMA) tool and SSMS (SQL Server Management Studio).

Note: DMA tool replaces the older Upgrade Advisor tool. To install DMA please see the following link https://docs.microsoft.com/en-us/sql/dma/dma-overview?view=sql-server-ver15.

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Azure SQL Database Networking

Have you realised the changes Microsoft have made to the firewall and networking section of Azure SQL Database? I found this quite stealthy and took me by surprise. I did encounter an edge case scenario where it lead to issues once I made some tweaks but that was a rare thing.

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Azure SQL Database – Error Logs?

Ok, so Azure SQL doesn’t really have its own error log based somewhere on a machine within \\MSSQL\Log directory but the closest thing you will get is a system catalog view called sys.event_log which is very useful. It will get you information about all sort of event types such as:

  • Successful connections
  • Failed connections
  • Throttling issues
  • Blocked by firewall attempts
  • Connection termination

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Azure SQL Database and Error Handling

For some reason I have friends / colleagues telling me that when scaling (up and down for this example) that no downtime occurs. Well, not only does Microsoft documentation say differently, I will show it. So let’s test it out. Before the practical test, this is the official stance. “There is a switch over period where connectivity is lost to the database for a short amount of time, which can be mitigated using retry logic”.

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