Azure Partner Community: SQL Server and Azure SQL Database

Welcome to part 1 of this month’s Azure Partner Community blog series, about data platforms and advanced analytics.


by Jonathan Gardner
US Partner Technology Strategist for Microsoft Azure

This month’s Azure Partner Community blog series will focus on data platforms and advanced analytics. In this post, I’ll explain the differences between SQL Server in Microsoft Azure and Azure SQL Database, and provide you with the considerations for selecting the right platform for your next data project. Look for more Azure Partner Community blog posts about data platforms and advanced analytics soon.

To SQL in Azure, or Azure SQL?

SQL Server hosted on-premises is a fantastic option, of course. But let’s talk about two Azure-related options you may not be aware of:

  • Hosting SQL Server on Azure Infrastructure as a Service
  • Azure SQL Database Platform as a Service

Deciding which to use can be a challenge, and as a former Database Administrator, I’ll give you a common DBA answer: “It depends.” I find the table below to be a helpful starting point for understanding how these options compare. You can review the detailed table here.

Azure SQL Database SQL Server in Azure VM

Best for:

  • New cloud-designed applications that have time constraints in development and marketing
  • Applications that need built-in high availability, disaster recovery, and upgrade mechanisms
  • Teams that do not want to manage the underlying operating system and configuration settings
  • Applications using scale-out patterns
  • Databases of up to 1 TB in size
  • Building Software-as-a-Service (SaaS) applications

Best for:

  • Existing applications that require fast migration to the cloud with minimal changes
  • SQL Server applications that require access to on-premises resources (such as Active Directory) from Azure via a secure tunnel
  • If you need a customized IT environment with full administrative rights
  • Rapid development and test scenarios when you do not want to buy on-premises non-production SQL Server hardware
  • Disaster recovery for on-premises SQL Server applications using backup to Azure Storage or AlwaysOn replicas with Azure VMs
  • Databases larger than 1 TB in size


The comparison above is helpful, but be aware that there is not yet feature parity between SQL Server and Azure SQL Database. Consult the Azure SQL Database General Limitations and Guidelines as part of your evaluation process.

Performance and the DTU

When we think about SQL Server on-premises, a major factor in sizing is disk performance. I/O tends to be the bottleneck in most SQL Server systems. When considering if Azure SQL Database is right for an application, evaluating the performance needs of the application is a logical place to start. Enter the Database Transaction Unit (DTU). Calculating performance based on traditional metrics was not a single story. In very basic terms, 1 DTU = 1 transaction per second.

Understanding DTUs

DTU Calculator

Benchmark overview for Azure SQL Database

SQL Server on Azure IaaS

While the DTU will govern the performance of Azure SQL Database, the type of VM and storage will be the driving factors of SQL Server hosted on IaaS. The carryover is that the same performance tuning options that are available to an on-premises deployment of SQL Server can be used in an IaaS deployment.

Performance best practices for SQL Server in Azure Virtual Machines

When deploying SQL Server on Azure IaaS, the initial thought is to deploy via the Marketplace through the portal. While this is a good option, many organizations need the ability to deploy customized SQL Server images or VMs. This scenario, as well as more complicated multi-server deployments, are possible using the Azure Resource Manager deployment model. Using Azure Resource Manager, you can create templates for deploying complex applications into Azure, dramatically increasing the flexibility that organizations have in how they use Azure.

Azure Resource Manager Architecture documentation

Additional documentation and videos

Azure Partner Readiness Catalog

SQL Database tutorial: Create a SQL Database in minutes using sample data and the Azure portal

Azure SQL Database dynamically scale-up or scale down

Watch video online

Deploying highly Available SQL Server in Microsoft Azure IaaS

Watch video online

Introduction to Azure Resource Manager

Watch video online


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