PROS

Managed service (low operational overhead)

AWS handles:

• OS patching

• SQL Server patching (CUs)

• Backups and retention

• Monitoring hooks

No need for Windows Server administration.

Built-in High Availability

• Multi-AZ deployments provide synchronous standby with automatic failover.

• Simpler than managing WSFC/AGs yourself.

Automated backups & point-in-time recovery

• Continuous backups to S3.

• PITR typically up to 35 days.

• No backup jobs or storage management required.

Faster provisioning

• New instances can be created in minutes.

• Easy scaling of storage (with some limits).

Integrated monitoring

• CloudWatch metrics, Performance Insights.

• Easier visibility without custom tooling.

Licensing simplicity

• License Included model available.

• Predictable costs if you don’t already own SQL licenses.

PROS

Full control

Complete access to:

• Windows OS

• Registry

• Storage layout

• SQL Server configuration

You can use every SQL Server feature.

Maximum SQL Server compatibility

Supports:

• Always On Availability Groups

• Failover Cluster Instances

• Log shipping

• Replication

• SSIS, SSAS, SSRS

Ideal for legacy or complex workloads.

Advanced performance tuning

Control over:

• Disk layout (tempdb, data, logs)

• IOPS provisioning

• NUMA and memory settings

Better suited for very high-performance or low-latency systems.

Flexible HA/DR architectures

You design the topology:

• Multi-AZ or Multi-Region AGs

• Hybrid DR (on-prem + AWS)

Easier to meet strict RPO/RTO requirements.

Cost optimisation options

• Bring Your Own License (BYOL).

• Use Reserved Instances / Savings Plans.

• More predictable cost control for large, steady workloads.

CONS

Limited SQL Server control

No access to:

• OS

• Registry

• File system outside RDS boundaries

Cannot use:

• SQL Server Agent jobs that access OS

• xp_cmdshell

• CLR with external access

• Custom trace flags (beyond what RDS allows)

Feature restrictions

Some SQL Server features are unavailable or constrained:

• No traditional Always On Availability Groups (RDS has its own HA model)

• No SSIS running on the same host

• Limited control over maintenance plans

Cross-instance features can be awkward.

Performance tuning limitations

You cannot:

• Tune Windows settings

• Control NUMA

• Install third-party agents (e.g., antivirus exclusions, monitoring agents)

Storage performance is abstracted; less predictable at extreme scale.

Less flexible DR strategies

DR is mostly:

• Read replicas

• Cross-region snapshot restore

No log shipping or custom AG topologies.

Cost at scale

RDS can become expensive for:

• Large instances

• High I/O workloads

• Long retention

License Included pricing is costly for SQL Enterprise Edition.

CONS

Higher operational burden

You are responsible for:

• OS patching

• SQL patching

• Backups

• Monitoring

• Security hardening

Requires stronger DBA + sysadmin skills.

HA/DR complexity

Always On and clustering require:

• Careful networking setup

• Manual testing

• Ongoing maintenance

Failovers are not “hands-off” by default.

Slower provisioning

• Building and configuring new servers takes longer.

• More moving parts to get right.

Risk of configuration drift

• Inconsistent builds if automation is weak.

• Greater chance of human error.

You own the blast radius

• Misconfiguration, failed patches, or missed backups are your responsibility.

Choose RDS if:

• You want minimal admin overhead.

• Your workload fits within RDS feature limits.

• You value simplicity over flexibility.

• You don’t need deep OS/SQL customisation.

Choose EC2 if:

• You need full SQL Server functionality.

• You run complex HA/DR setups.

• Performance tuning is critical.

• You already manage SQL Server at scale (and possibly have licenses).