The Three Options
When moving SQL Server workloads to Azure, you have three main options under the "Azure SQL" umbrella. It's important to understand what each one actually is:
Azure SQL Database
Fully managed, serverless or provisioned. Microsoft handles OS patches, SQL upgrades, backups, and HA. You manage only the database and schema.
Azure SQL Managed Instance
Near-100% SQL Server compatibility in a fully managed environment. Best for lift-and-shift of on-premises instances with minimal code changes.
SQL Server on Azure VM
A full SQL Server installation on a Windows or Linux VM. You control everything — OS, SQL version, configuration, extensions. Microsoft offers the SQL IaaS Agent extension for automated backups and licensing benefits.
This article focuses on the most common decision: Azure SQL Database vs SQL Server on Azure VM. Managed Instance sits between the two and deserves its own article.
Head-to-Head Comparison
| Factor | Azure SQL Database | SQL Server on VM |
|---|---|---|
| Management overhead | Very low — fully managed | High — you manage OS, SQL, patches |
| SQL Server compatibility | Partial — no SQL Agent, no cross-db queries, no CLR by default | Full — identical to on-premises |
| Cost (small workloads) | Lower — serverless scales to zero | Higher — VM runs 24/7 |
| Cost (large workloads) | Can be expensive — DTU/vCore pricing | Predictable — fixed VM cost |
| High availability | Built-in — 99.99% SLA | Manual setup — Always On AG required |
| Backup & recovery | Automatic — point-in-time restore included | Manual or automated via Azure Backup |
| Scaling | Near-instant — vCore slider | VM resize required — involves restart |
| OS-level access | None | Full RDP/SSH access |
| Custom SQL features | Limited — no linked servers, limited CLR | Everything — SSIS, Replication, CDC, etc. |
| Licensing | Included in price | BYOL with Azure Hybrid Benefit or pay-as-you-go |
When to Choose Azure SQL Database
Azure SQL Database is the right choice when:
- You're building a new application without legacy SQL Server dependencies
- Your workload is unpredictable or bursty — serverless tier scales to zero when idle
- Your team has no DBA capacity and wants zero maintenance overhead
- You need instant global scale via Hyperscale or Geo-Replication
- The database is self-contained — no cross-database queries, no linked servers
- You want the highest possible SLA (99.995%) with Business Critical tier
The Serverless tier of Azure SQL Database automatically pauses compute when inactive and resumes in seconds. For development databases or low-traffic workloads, this can reduce costs by 70-80% compared to a provisioned VM.
When to Choose SQL Server on Azure VM
SQL Server on a VM is the right choice when:
- You're doing a lift-and-shift of an existing on-premises SQL Server instance
- Your application uses SQL Server Agent jobs, linked servers, or SSIS packages
- You need specific SQL Server versions (e.g. 2016 for a legacy application)
- You have existing SQL Server licences and want to use Azure Hybrid Benefit
- Your workload uses features not available in PaaS: CLR, Change Data Capture, replication, etc.
- You need OS-level access for third-party tools, agents, or compliance requirements
- You're running multiple databases that share resources and cross-reference each other
Migrating a complex on-premises SQL Server instance to Azure SQL Database often requires significant application changes. If your timeline is tight or your application is large, SQL Server on VM is almost always the safer first step — you can always migrate to PaaS later.
The Hidden Cost Trap
Many teams choose Azure SQL Database expecting it to be cheaper, then get a nasty surprise when their workload grows. Here's why:
A General Purpose Azure SQL Database with 8 vCores costs around €900–1,100/month. A Standard_D8s_v3 VM (8 vCores, 32 GB RAM) with SQL Server Standard costs around €500–700/month using Azure Hybrid Benefit — significantly less, with more control.
The break-even point depends on your workload, but for databases above 4 vCores running 24/7, SQL Server on VM is often more cost-effective when you factor in the Azure Hybrid Benefit for existing SQL Server licence holders.
The Right Decision Framework
Ask yourself these questions in order:
- Do you need features unavailable in PaaS? (SQL Agent, linked servers, replication, CLR) → VM
- Are you lifting and shifting an existing instance? → VM or Managed Instance
- Is this a new greenfield application? → SQL Database (start here, move to VM only if needed)
- Is the workload bursty or dev/test? → SQL Database Serverless
- Do you have existing SQL licences? → VM with Azure Hybrid Benefit
Summary
Neither option is universally better. Azure SQL Database excels for new applications, variable workloads, and teams that want zero DBA overhead. SQL Server on VM is the safer, more flexible choice for migrations, complex instances, and workloads that need full SQL Server compatibility.
If you're unsure which is right for your workload, talk to our Azure team — we've helped dozens of companies make this decision and avoid expensive mistakes.