AWS RDS vs EC2: Fully Managed vs Self Managed Database
While RDS offers ease of management but less control, the self-managed database on EC2 is completely the opposite. Let's see the detailed comparison to help us choose the best approach for our needs.
Management and administration
RDS: It is easy to set up, AWS helps automate daily backups, provisioning, OS patching, point-in-time restore, snapshots… AWS also takes care of the heavy lifting of running the database, such as failover, recovery, scaling, performance tuning…
EC2 (Self-managed Database): We have full control of the OS (OS type, version, patch, upgrade…), but we have to do everything that AWS does for us if we are using RDS. Which can lead to maintenance overhead.
High Availability
RDS: AWS has built-in multi-AZ deployment support that provides automatic failover. This process is automated with a minimal chance of disrupting the applications.
EC2 (Self-managed Database): we are responsible for implementing HA (high availability) like replication, load balancing, and failover. Require additional setup for high-availability cluster environments. All these mechanisms must be configured and managed by the user.
Backup and Recovery
RDS: Automated daily backups and point-in-time recovery are built-in features.?Snapshots can be taken manually and stored in S3. Recovery from backups is a fully managed process by AWS. We can use CloudWatch to receive backup notification events such as success, failure to back up…
EC2 (Self-managed Database): need to manually set up our own backup solution. Also have to manually manage the backup scheduling, storage, and restoration process. Cannot use CloudWatch in this case.
Scalability
RDS: Vertical scaling (resizing the instance type) is easy. Horizontal scaling (read replicas) is supported for read-heavy workloads. Automatic storage scaling when the storage is nearly full.
EC2: Vertical scaling (resizing EC2 instance) requires stopping and restarting the instance, which causes downtime. Horizontal scaling (adding more EC2 instances) is entirely manual and requires configuring database replication.
Support and Control
RDS: Limited control of the underlying hardware and OS configuration. We cannot have direct access to the underlying host for advanced customization.
EC2: we have full control over the database and the OS, allowing for the advanced customization that RDS does not support.
We can install any OS, any version, and any database software.
Performance
RDS: Optimized for general-purpose database workloads. We can provision the IOPS or general-purpose SSDs. It has built-in monitoring integration with CloudWatch.
EC2: we have to predict the IOPS we need. We do not have built-in integration with CloudWatch, we need to deploy the 3rd party monitoring tool.
Security
RDS: RDS handles encryption at rest (with AWS KMS) and in transit. Security updates and patches are automatically applied.
EC2: We have to manually configure and manage database encryption, secure access, and firewall settings.
We must handle security patches and OS updates.
The encryption process is at EBS volume, and we can also configure the encryption process at the database level.
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Storage
RDS: We have 3 options:
EC2: the IOPS depends on the attached EBS storage type. We can achieve a maximum of 256,000 (16 KiB I/O) and a throughput of 4,000 MiB/s.
Licensing
RDS: AWS supports the "Bring Your Own License" (BYOL) model, but it does not have full license support for some database editions.
EC2: we can bring our own license for any database edition or any database tools.
Cost
We can estimate the cost using the AWS cost calculator
EC2
For RDS
This is the price comparison I got from the internet Amazon RDS vs EC2: Top 9 Differences You Must Know - WebScoot.io. It can be outdated, but it still reflects the differences between price of fully managed RDS and self-managed database on EC2 instance.
Comparison
RDS can be more expensive due to the managed service overhead, but it reduces administrative costs. We pay for instance usage, storage, backups, and data transfer. Free tier option for low-scale databases, but pricing increases with additional features (e.g., Multi-AZ, high IOPS storage).
EC2 instances may have lower upfront costs, but administrative overhead (management, scaling, backups) adds long-term costs. We pay for the EC2 instance, storage (e.g., EBS volumes), and any additional data transfer. If we need a highly customized setup and have a skilled database team, EC2 may offer cost savings.
Responsibility between AWS and the user.
Decision-making diagram and decision matrix
https://docs.aws.amazon.com/prescriptive-guidance/latest/migration-sql-server/comparison.html#matrix
Conclusion
Use RDS: If we need a managed service that takes care of operational tasks like backups, updates, and scaling, and our workload is compatible with the limitations of a managed service.
Use EC2: If we need complete control over the database environment, have specific custom requirements, or are comfortable with managing and maintaining our database infrastructure manually.