Azure VM vs Azure SQL Database

Compare SQL Server on Azure VM vs Azure SQL DB

Features

SQL Server on Azure VM

Azure SQL Database

Deployment

User deploys an Azure VM (with a SQL image if desired) – similar to EC2, quick to create but you manage SQL setup.

Instant provisioning of a database via portal/CLI – ready in minutes, no VM or OS to manage (fully platform-managed).

Management

Self-managed, though Azure offers a VM extension for automating SQL patching/backups.

Fully managed by Azure – Microsoft handles all patching and maintenance.

Customization

Maximum – complete OS and SQL control, legacy versions supported.

Very restricted – no OS or instance access, only DB-scoped settings; cannot use unsupported features (e.g., CLR, xp_cmdshell).

Use Case

When full control is needed in Azure (legacy apps, custom integrations, SSRS/SSAS); a bridge between on-prem and cloud with control.

Best for new cloud-native apps, SaaS, and scenarios requiring zero infrastructure management – modern applications that can live within one DB (or use sharding/pools).

Maintenance Responsibility

You/your team – unless using Azure’s IaaS Agent to auto-patch, you handle updates.

Microsoft – fully automatic patch management and updates (you don’t even see it happening).

Operational Control

Full control – you can even remote desktop to OS and change anything.

Partial – you have db_owner on your databases and a contained “server” admin, but many instance-level features aren’t available (no control over master/tempdb beyond some settings).

Backups

User-managed (can use Azure Backup or SQL Agent jobs, or enable the SQL VM backup extension for Azure-managed backups)

Automated: full PITR backups are done by Azure (e.g., every 5-10 min log backups); long-term retention can be configured for weekly/monthly/yearly backups.

Scalability

Vertical: change VM size (reboot required); Horizontal: add more VMs (e.g., Always On AG for read scale) – manual setup.

Vertical: move between DTU/vCore tiers easily (some operations online); Horizontal: scale out by sharding or using multiple databases (Elastic Pool), or use readable geo-replicas – not transparent sharding, app must handle if needed.

Performance

High (depends on chosen VM and disks): you can use Premium SSD/Ultra Disk on Azure VMs and optimize like on-prem – performance is as good as the hardware allows, with full control.

Excellent for typical workloads, with options to choose higher tiers if needed: Business Critical has low-latency SSD and 2-4 replicas for read, Hyperscale can scale out readers and handle very large DBs. The platform handles tuning, but you might sacrifice some extreme tuning (e.g., can’t control file placement).

Elasticity

No native auto-scale – you set a VM size; possible to script something with Azure Automation to scale VMs on a schedule or metric, but it’s user-implemented.

Yes (Serverless option) – Azure SQL DB serverless will auto-scale CPU/RAM within set bounds and even pause the DB on inactivity, providing true on-demand elasticity. For provisioned databases, you can scale with an API call (not automatic, but quick) and use Azure Automation to schedule or trigger it.

SQL Server Version

Any version (since you control the install media). Azure marketplace images cover currently supported versions (2012+), but you could bring older versions on a custom image if absolutely needed.

Azure SQL Database always runs the latest stable SQL Server engine managed by Microsoft. It doesn’t match a specific legacy version but supports compatibility levels up to 160 (SQL 2022) for older T-SQL compatibility.

SQL Feature Support

All on-box features supported – you can install SSRS on the VM, use SSIS, enable ML Services, etc., just as on a normal server. No limitations beyond what SQL Server normally has.

Azure SQL DB supports most SQL features but lacks SQL Agent, CLR assemblies, FILESTREAM, and cross-database transactions. Features like JSON, Full-Text Search, In-Memory OLTP, and Temporal Tables are fully supported.

Cross-Database Queries

Yes, within the SQL instance on that VM you can do cross-database joins/transactions.

No (not directly): each Azure SQL DB is isolated. Cross-DB joins require external tables or client-side join logic. Azure provides elastic query which is essentially a workaround (create external data source to another DB). So it’s not as seamless as on a full instance.

Custom Software

Yes – you can treat it like any Windows server: for example, install Splunk forwarders, custom performance collectors, or even run other apps on the same VM (if resources allow).

No – you get only the database environment. If you need something like a specialized full-text extender or a custom compression DLL, you can’t install that on Azure SQL DB. You’d have to move to MI or VM if installation is required.

Network Configuration

Runs in Azure VNet – full control over IP address, subnet, NSGs, etc., like any VM. You can even place multiple VMs in the same subnet for cluster setups. Connect via ExpressRoute/VPN to on-prem easily.

By default, accessible over the internet with a secure endpoint (you restrict by firewall rules). If needed, use Private Link to bring it into your VNet with a private IP. You don’t see or manage the underlying network, but you can control connectivity at a high level (public/private).

Security

Similar to EC2: you manage OS hardening, patches, SQL security config. Azure can encrypt disks by default, and you can use Azure Key Vault for TDE keys. Azure VM itself is an isolated environment you control. Compliance again is on how you set it up (Azure just provides infrastructure that can be compliant if you configure it so).

Azure SQL DB enforces TDE for data at rest, encrypted connections, and compliance with PCI DSS, HIPAA, etc. Auditing and Advanced Threat Protection enhance security, while Private Link restricts network access. As a multi-tenant service, OS-level access is not available, but Microsoft ensures data isolation and certification compliance.

Authentication

Windows Auth and SQL Auth supported – join the VM to a domain (on-prem AD or Azure AD Domain Services) and you get integrated security. You can also use contained database users, etc., just like on-prem.

Supports SQL authentication and Azure AD authentication, allowing Azure AD users to log in with modern identity management and MFA. Traditional Windows AD accounts require syncing to Azure AD for authentication.

High Availability

Must be configured by user – e.g., Always On AG across VMs or a Failover Cluster with Azure Shared Disks or Azure FSx for SMB. Azure provides multi-AZ (multi-zone) VM placement for resilience, but SQL HA is your responsibility.

Azure SQL DB provides built-in HA with at least three replicas: General Purpose uses Azure storage redundancy, while Business Critical employs a 3-4 node Always On quorum with 99.99% SLA. Failovers are automatic with minimal impact.

Disaster Recovery

User-defined: e.g., use Azure Site Recovery to replicate the VM to another region, or set up an AG with a replica in a secondary region for DR. Azure won’t auto-handle cross-region failover for VMs – your DR plan executes it.

Supports Active Geo-Replication with up to 4 readable replicas in different regions. Failover can be manual or automated via Auto-Failover Groups. If not configured, point-in-time restore to another region serves as a DR option.

Pricing

Pay for Azure VM + storage. E.g., ~$1.5-2k/month for 8 vCPU VM with SQL Std included. Using Hybrid Benefit (BYOL) might drop that to ~$1k (just VM). Azure RIs can save ~30%. Network egress (if any) is extra.

Azure SQL DB pricing is based on compute (vCores or DTUs) and storage. An 8 vCore General Purpose database with 4TB costs ~$1,800/month, while Business Critical is 2-3× higher due to extra replicas and SSDs. Hyperscale storage is charged per GB, but compute is similar to General Purpose. SQL licensing is included.

Licensing Model

License-Included or BYOL. Azure Hybrid Benefit lets you apply existing licenses; or pay-as-you-go includes SQL license. Per-second billing. Enterprise Agreement customers can also get dev/test pricing without SQL costs on Azure for non-prod.

Azure SQL DB follows a license-included model, but Azure Hybrid Benefit reduces costs if you bring existing licenses. Billing is pay-as-you-go or reserved capacity (1-3 years). There are no CALs, and Enterprise Edition (SA) holders get cost breaks on Business Critical.

Pricing Comparison of Database Configuration

8vCore + 4TB Data size + Backup,  Single Instance

~$1,700/month for 8 vCore GP Azure MI or SQL DB (license included);
~$1,500/month for Azure VM (license included) or ~$1,000 with BYOL.
On-prem ~$1k (Std) as above.

An 8 vCore, 4TB General Purpose Azure SQL DB costs ~$1,800/month ($1,400 compute + $400 storage).
Switching to Business Critical raises the price to $4,000–$5,000/month. Hybrid Benefit can cut vCore costs by ~40%.

8vCore + 4TB Data size + Backup + DR/HA

HA requires a secondary VM (8 vCore + 4TB) but incurs no extra SQL Server license cost if using Azure Hybrid Benefit.
For DR, a geo-replicated secondary adds ~$1,800/month, bringing total costs to ~$3,400/month (excluding SQL license).
Backup adds ~$120/month. Without Azure Hybrid Benefit, SQL Server licensing adds ~$2,500/month, pushing total cost to ~$5,900/month.
DR and HA both require paying for full VM resources; SQL license charges apply to all nodes unless covered by Hybrid Benefit.

HA is included at no extra cost. For DR, a geo-replicated secondary (8 vCore GP instance) adds ~$1,800/month, bringing total costs to $3,600/month.
Auto-Failover Groups require paying for both primary & secondary. Business Critical geo-secondaries cost the full BC rate.