When you're moving SQL to Azure, you'll face a lot of choices. Azure has several different ways you can run SQL, with each own tradeoffs around control, compatibility, cost, and how much day-to-day work is involved. If you focus only on moving quickly, you might end up with higher costs down the road, run into missing features, or give yourself more maintenance headaches than expected.
Before you start comparing the different products, step back and think about what you really need to accomplish. As you weigh your options, keep these three big requirements in mind:
1. Scalability and cost shape
Decide early on if you'll need to scale up (make a server bigger) or scale out (spread across more servers). Scaling up is usually easier, while scaling out gives you more flexibility, but might mean changing your application and being more disciplined operationally. Think about your workload: if it's pretty steady, provisioned compute is a good fit; if it varies a lot, you'll want something more flexible. Picking the wrong cost model can lead to surprise expenses, even long after your migration is done.
2. Availability and recovery targets
When it comes to availability, you need to think about both uptime and how quickly you can recover if something goes wrong. Make sure your choice matches your recovery point and recovery time goals, your need for failover, and whether you need read replicas. Some setups are all about high performance and resilience with lots of replicas; others are designed for big scale and fast backup or restore. If your business can't handle long recovery times, make that a top-level requirement from the start.
When it comes to availability, you need to think about both uptime and how quickly you can recover if something goes wrong. Make sure your choice matches your recovery point and recovery time goals, your need for failover, and whether you need read replicas. Some setups are all about high performance and resilience with lots of replicas; others are designed for big scale and fast backup or restore. If your business can't handle long recovery times, make that a top-level requirement from the start.
3. Security, compliance, and data protection
Security, compliance, and data protection are critical—don't leave them as an afterthought. Think about how you’ll encrypt data at rest, when it’s moving, and even when it’s in use. Make sure you have secure connections (TLS), know how your data is encrypted on disk, and who manages the keys—sometimes you’ll need to manage them yourself. Combine these with things like identity controls, network isolation, audit records, and monitoring. The earlier you plan for security, the less pain (and cost) you'll have later.
Security, compliance, and data protection are critical—don't leave them as an afterthought. Think about how you’ll encrypt data at rest, when it’s moving, and even when it’s in use. Make sure you have secure connections (TLS), know how your data is encrypted on disk, and who manages the keys—sometimes you’ll need to manage them yourself. Combine these with things like identity controls, network isolation, audit records, and monitoring. The earlier you plan for security, the less pain (and cost) you'll have later.
Once you've got these three areas covered, you can pick the SQL option that actually fits your situation—instead of just following what looks easiest.
Azure SQL Database: cloud-first, database-scoped PaaS
Azure SQL Database is a fully managed service, so you don’t have to worry about the underlying operating system or the SQL Server instance itself. It’s a great fit for modern apps that can treat the database as just a single unit and take advantage of built-in elasticity. This option really shines if your team wants to spend less time patching and maintaining and more time building features. If you have lots of similar databases (like one per customer or region), elastic pools let you share resources easily and keep costs under control.
Azure SQL Database is a fully managed service, so you don’t have to worry about the underlying operating system or the SQL Server instance itself. It’s a great fit for modern apps that can treat the database as just a single unit and take advantage of built-in elasticity. This option really shines if your team wants to spend less time patching and maintaining and more time building features. If you have lots of similar databases (like one per customer or region), elastic pools let you share resources easily and keep costs under control.
Azure SQL Managed Instance: lift-and-shift with instance features
Managed Instance is also a platform service, but it gives you a whole SQL Server instance boundary to work with—so it’s meant for migrations where you don’t want to redesign too much. It’s especially handy if you rely on features like SQL Server Agent, CLR, Database Mail, distributed transactions, or other things that don’t fit easily into the single-database model. You can run multiple databases on the same instance, which can make migrations and operations simpler.
Managed Instance is also a platform service, but it gives you a whole SQL Server instance boundary to work with—so it’s meant for migrations where you don’t want to redesign too much. It’s especially handy if you rely on features like SQL Server Agent, CLR, Database Mail, distributed transactions, or other things that don’t fit easily into the single-database model. You can run multiple databases on the same instance, which can make migrations and operations simpler.
SQL Server on Azure Virtual Machines: maximum control and... responsibility
If you need maximum control, SQL Server on Azure Virtual Machines gives you full access to both the OS and SQL Server—so you can do whatever you want with versions, custom agents, or tricky extensions that are hard to refactor. But keep in mind, you’ll be on the hook for patching, backups, and keeping things available, just like you would if it were running on-premises. This setup is usually for legacy workloads, complicated vendor software, or really customized environments.
If you need maximum control, SQL Server on Azure Virtual Machines gives you full access to both the OS and SQL Server—so you can do whatever you want with versions, custom agents, or tricky extensions that are hard to refactor. But keep in mind, you’ll be on the hook for patching, backups, and keeping things available, just like you would if it were running on-premises. This setup is usually for legacy workloads, complicated vendor software, or really customized environments.
Sanity check
And just to sanity check: sometimes a traditional relational database isn’t the right fit. If you need global distribution, super low latency between regions, flexible schemas, or massive horizontal scaling, you might actually be better off with a NoSQL service instead.
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