Three targets, one assessment
Microsoft groups its SQL Server cloud targets under the Azure SQL family: Azure SQL Database, Azure SQL Managed Instance and SQL Server on Azure VMs, all built on the SQL Server database engine (Microsoft Learn, What is Azure SQL?, accessed 2026-10-20). The question is not which product is newer but which one each database can run on without rework, and that is answered by evidence rather than preference. EPC Group's Azure consulting practice runs the decision in four steps: discover every instance and database, assess feature use and performance against all three targets, group databases that must move together, and set a downtime budget per application that selects the migration method. Most estates end up on more than one target. Line-of-business databases with instance-level dependencies go to Managed Instance, vendor applications that need operating system access stay on virtual machines, and new or refactored applications go to Azure SQL Database.
Comparing the three targets
Microsoft's comparison draws the lines clearly. Azure SQL Database is a platform service based on the latest stable Enterprise Edition engine, offered as single databases or elastic pools, with Hyperscale and serverless options; it supports most database-level capabilities, but migration can be challenging for applications with operating system or SQL Agent dependencies, and databases can reach 128 TB. Azure SQL Managed Instance supports almost all instance-level and database-level capabilities, sits on a private IP address in an Azure virtual network, and reaches 16 TB; Microsoft positions it for most migrations to the cloud. SQL Server on Azure VMs gives full parity with the matching on-premises version, full control of the engine and operating system, and up to 256 TB, but backups and high availability become the customer's job (Microsoft Learn, What is Azure SQL?, accessed 2026-10-20).
The Managed Instance migration guide adds the deciding conditions. Move to a VM instead when the workload needs operating system or file system access, depends on FileStream or FileTable, PolyBase or cross-instance transactions, must stay on a specific SQL Server version, or needs far less compute than a managed instance offers. Within Managed Instance, the baseline I/O latency picks the tier: General Purpose for latency greater than 5 ms, Business Critical for latency less than 3 ms, and In-Memory OLTP is available only in Business Critical (Microsoft Learn, Migration overview: SQL Server to Azure SQL Managed Instance, accessed 2026-10-20).
The assessment: discovery, readiness and sizing
Microsoft frames a SQL Server migration in five phases: discovery, business case, assessment, conversion and migration. Discovery uses the Azure Migrate appliance, which finds instances and databases without installing anything on the servers and works across VMware, Hyper-V and physical environments. Assessment, run through Azure Migrate or Azure Arc, measures readiness for each target and sizes a service tier and SKU using either the on-premises configuration or collected performance data. Conversion is not needed for SQL Server sources (Microsoft Learn, Migration overview: From SQL Server, accessed 2026-10-20). Microsoft's current tool comparison positions Azure Migrate for discovery and assessment at scale, including deployment recommendations, target sizing and monthly estimates that account for licensing benefits, and Azure DMS and Azure Arc for moving SQL Server objects to SQL Database or Managed Instance (Microsoft Learn, Compare SQL data migration tools, accessed 2026-10-20). EPC Group prefers performance-based sizing collected across a month-end or other peak period, because as-configured sizing copies whatever over-provisioning exists today.
Instance-level dependencies: SQL Agent, linked servers and CLR
Instance-scoped features are where target choices are usually made. Azure SQL Database has no SQL Server Agent and points to elastic jobs instead, has no linked servers and offers elastic query as the alternative, does not support CLR, and does not support cross-database three-part-name queries. Azure SQL Managed Instance supports SQL Server Agent with documented differences, cross-database queries within the instance, linked servers only to SQL Server and SQL Database without distributed transactions, Database Mail, and CLR without file system access in CREATE ASSEMBLY (Microsoft Learn, Features comparison: Azure SQL Database and Azure SQL Managed Instance, accessed 2026-10-20). Restoring system databases to Managed Instance is not supported, so logins, SQL Agent jobs, operators and server-level triggers in master and msdb are scripted and recreated; the offline Azure DMS option migrates SQL Agent jobs, but only those with T-SQL steps, and jobs with SSIS package steps are moved by hand (Microsoft Learn, Migration overview: SQL Server to Azure SQL Managed Instance, accessed 2026-10-20).
Downtime: offline, online and log-based methods
The acceptable outage selects the method. Native backup and restore of .bak files is the simplest option and requires downtime for a full backup and restore. The Log Replay Service, based on SQL Server log-shipping technology, restores full, differential and log backups from Azure Blob Storage over a public endpoint, but the databases stay in restoring mode until it finishes and system updates or failovers can interrupt it. The Managed Instance link uses distributed availability groups to keep a readable replica in sync in near real time, has no fixed time limit, and offers the minimum-downtime cutover (Microsoft Learn, Migration overview: SQL Server to Azure SQL Managed Instance, accessed 2026-10-20). Azure DMS supports offline migration to all three targets and online migration to Managed Instance and Azure VMs (Microsoft Learn, Migration overview: From SQL Server, accessed 2026-10-20). EPC Group's cloud migration team rehearses every cutover on a copy before scheduling the real one.
Cost model inputs, as Microsoft describes them
This section lists only the cost levers Microsoft documents, with no prices. Azure SQL Database and Managed Instance are billed hourly by service tier and compute size under the DTU or vCore purchasing models, while SQL Server on Azure VMs is billed by VM size and either a license included in the image or an existing license (Microsoft Learn, What is Azure SQL?, accessed 2026-10-20). Azure Hybrid Benefit lets Software Assurance customers allocate SQL Server licenses to Azure SQL with no downtime to enable it; one Enterprise Edition core on-premises maps to four vCores in General Purpose or one in Business Critical (Microsoft Learn, Azure Hybrid Benefit - Azure SQL Database & SQL Managed Instance, accessed 2026-10-20). Reservations commit to one or three years of vCore compute for a region, deployment type and tier, apply automatically to matching resources, keep vCore size flexibility, and cannot cover DTU-based databases (Microsoft Learn, Save on compute costs with Azure Reservations - Azure SQL Database & SQL Managed Instance, accessed 2026-10-20). EPC Group models each option from the assessment output and the client's own licensing records.
Documented work
ANON-CASES: EPC Group engagement data for SQL Server migration covers mid-size and large manufacturing organizations moving on-premises SQL Server estates with SQL Agent, linked server and SSIS dependencies to a mix of Azure SQL Managed Instance and SQL Server on Azure VMs, delivered by the firm's Azure consulting practice. Client names are not published here. Engagements are described by industry and organization size only, and no outcome figures are quoted that cannot be traced to a signed deliverable. EPC Group is a Microsoft Solutions Partner with all six Solutions Partner Designations as of October 2026.
Primary sources
- What is Azure SQL? — Microsoft Learn, accessed 2026-10-20
- Migration overview: SQL Server to Azure SQL Managed Instance — Microsoft Learn, accessed 2026-10-20
- Features comparison: Azure SQL Database and Azure SQL Managed Instance — Microsoft Learn, accessed 2026-10-20
- Migration overview: From SQL Server — Microsoft Learn, accessed 2026-10-20
- Compare SQL data migration tools — Microsoft Learn, accessed 2026-10-20
- Azure Hybrid Benefit - Azure SQL Database & SQL Managed Instance — Microsoft Learn, accessed 2026-10-20
- Save on compute costs with Azure Reservations - Azure SQL Database & SQL Managed Instance — Microsoft Learn, accessed 2026-10-20
Frequently Asked Questions
What are the differences between Azure SQL Database, Managed Instance and SQL Server on Azure VMs?
Azure SQL Database is a fully managed database service for cloud applications, with serverless compute, elastic pools and Hyperscale, and databases of up to 128 TB. Azure SQL Managed Instance is a managed instance with almost complete SQL Server engine compatibility, native virtual network support and up to 16 TB, which Microsoft positions for most migrations to the cloud. SQL Server on Azure VMs is infrastructure as a service with full engine and operating system control, full version parity and instances of up to 256 TB, at the cost of managing patching, backups and high availability yourself (Microsoft Learn, What is Azure SQL?, accessed 2026-10-20).
How does the Azure Migrate or Data Migration Assistant assessment work?
Microsoft describes five phases: discovery, business case, assessment, conversion and migration. The Azure Migrate appliance discovers SQL Server instances without installing agents, and assessments run through Azure Migrate or Azure Arc, using either as-on-premises or performance-based sizing to recommend a deployment type, service tier and SKU size (Microsoft Learn, Migration overview: From SQL Server, accessed 2026-10-20). Microsoft compares the current tools side by side: Azure Migrate assesses at scale and provides deployment recommendations, target sizing and monthly estimates, while Azure DMS and Azure Arc perform migrations (Microsoft Learn, Compare SQL data migration tools, accessed 2026-10-20). EPC Group runs performance-based assessments over a full business cycle.
How are SQL Agent jobs, linked servers and CLR handled?
Azure SQL Database has no SQL Server Agent (elastic jobs replace it), no linked servers (elastic query is the alternative) and no CLR. Azure SQL Managed Instance supports SQL Server Agent with documented differences, linked servers only to SQL Server and SQL Database without distributed transactions, and CLR without file system access in CREATE ASSEMBLY (Microsoft Learn, Features comparison: Azure SQL Database and Azure SQL Managed Instance, accessed 2026-10-20). For Managed Instance, the offline Azure Database Migration Service migrates SQL Agent jobs with T-SQL steps only, and instance-level objects in master and msdb must be scripted and recreated (Microsoft Learn, Migration overview: SQL Server to Azure SQL Managed Instance, accessed 2026-10-20).
What are the downtime options: offline, online and log shipping?
Offline options include native backup and restore, BACPAC and offline Azure DMS, where downtime covers a full backup and restore. The Log Replay Service uses SQL Server log-shipping technology to restore full, differential and log backups from Azure Blob Storage, but databases stay in restoring mode until the process completes. The Managed Instance link uses distributed availability groups to replicate changes in near real time, keeps the target readable during migration and lets the cutover happen at any time (Microsoft Learn, Migration overview: SQL Server to Azure SQL Managed Instance, accessed 2026-10-20). Azure DMS also supports online migrations for Managed Instance and Azure VMs (Microsoft Learn, Migration overview: From SQL Server, accessed 2026-10-20).
How is cost modeled: vCore, reserved capacity and Azure Hybrid Benefit (as Microsoft describes them)?
Microsoft bills Azure SQL Database and Managed Instance hourly by service tier and compute size, under the DTU or vCore purchasing models (Microsoft Learn, What is Azure SQL?, accessed 2026-10-20). Azure Hybrid Benefit allocates Software Assurance SQL Server licenses to Azure SQL; for SQL Database it applies only to provisioned vCore compute, not DTU or serverless, and it includes a 180-day migration allowance (Microsoft Learn, Azure Hybrid Benefit - Azure SQL Database & SQL Managed Instance, accessed 2026-10-20). Reservations commit to one or three years of vCore compute by region and tier and exclude software, networking and storage (Microsoft Learn, Save on compute costs with Azure Reservations - Azure SQL Database & SQL Managed Instance, accessed 2026-10-20).
Talk to a senior architect
If your SQL Server estate is approaching a hardware refresh or an end-of-support deadline, a 30-minute discovery call with a senior EPC Group architect outlines the assessment, the likely target for each database group and the cutover method that fits your downtime budget. See the Azure consulting service hub for engagement structures.
Email contact@epcgroup.net or call 888-381-9725.
a Microsoft Gold Partner (2000 until Microsoft retired the program in 2022) — today holding all six Microsoft Solutions Partner Designations.