Migrating SQL Server to Azure: What Are the Options

The database is the heart of the migration

In almost every migration project, SQL Server is the most critical workload and the one that most influences cost and risk. Migrating it well can significantly reduce operational cost and gain high availability effortlessly; migrating it poorly causes downtime and rework. Azure offers three main destinations, and choosing the right one depends on compatibility, control, and appetite for management.

As a Microsoft partner and CSP, RHC drives this choice with technical and cost assessment, applying Azure Hybrid Benefit to reduce the bill.

The three options

1. SQL Server on a virtual machine (IaaS)

This is the rehost of the database: you install SQL Server on a Windows or Linux VM in Azure, exactly as in the datacenter. Advantages:

• Full compatibility — any version, feature, or special configuration works.
• OS control — needed for applications that require OS access or specific agents.
• Fast migration — ideal when the deadline is short.

Downside: you remain responsible for patches, backups, high availability, and tuning. It is the lowest-effort migration destination, but the highest ongoing operational effort.

2. Azure SQL Managed Instance

Managed Instance is the perfect middle ground for most migrations: a PaaS service with near-100% compatibility with traditional SQL Server, including instance features like SQL Agent, cross-database queries, and CLR. You gain:

• Built-in high availability without configuring a cluster.
• Automatic backups and Microsoft-managed patching.
• Migration with little or no code change.
• Network isolation via VNet.

It is the default recommendation for those who want to leave server administration behind without rewriting the application. Azure Hybrid Benefit significantly reduces the license cost here.

3. Azure SQL Database

Azure SQL Database is PaaS at the individual database level, the most modern and elastic. It does not expose instance features (like SQL Agent in the same model), so it may require application adjustments. In return, it offers:

• Elastic scalability and flexible purchase models (vCore, DTU, serverless).
• Serverless that pauses when idle, saving on intermittent workloads.
• High availability and minimal management.
• Advanced features like Elastic Pools to consolidate many databases.

It is ideal for new or modernized applications, born for the cloud.

How to choose

The decision follows a clear logic:

1. Does the application require OS access or very specific features? → SQL on a VM.
2. Do you want to leave administration behind without rewriting and keep instance dependencies? → Managed Instance.
3. Is the application modern or being modernized and seeking maximum elasticity? → Azure SQL Database.

In most enterprise projects, Managed Instance is the balance point between compatibility and PaaS benefit.

The migration process

Regardless of destination, database migration follows stages:

1. Compatibility assessment — the Data Migration Assistant identifies blockers and needed adjustments.
2. Sizing — define service tier, vCores, and storage based on real consumption.
3. Schema and data migration — using Azure Database Migration Service to minimize downtime.
4. Online vs. offline migration — online keeps the database synchronized until cutover, reducing the window.
5. Validation and cutover — test integrity and performance before the final switch.
6. Optimization — tune indexes, tier, and apply Hybrid Benefit and reservations.

Cost and licensing

Azure Hybrid Benefit is decisive in database cost. It lets you reuse SQL Server licenses with Software Assurance, removing the license cost from the service price — frequent 30–50% savings on the license portion. Combined with reserved capacity (the database equivalent of a reserved instance), the total cost drops further for stable workloads.

Checklist / Key takeaways

• Three destinations: SQL on a VM, Managed Instance, and Azure SQL Database.
• VM for full compatibility and OS control; higher operational effort.
• Managed Instance is the balance: near-100% compatible PaaS.
• Azure SQL Database for modern applications and maximum elasticity.
• Use Data Migration Assistant and Database Migration Service in the process.
• Apply Azure Hybrid Benefit and reserved capacity to cut cost.

RHC assesses compatibility, sizes the destination, and runs the database migration with the least possible downtime, capturing licensing savings along the way.