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MySQL 8.0 to Aurora 3 Migration: The Complete Problem-Solver's Guide (2025)

Last updated: July 2025  |  Read time: 14 min  |  Author: Database Architecture Desk

Why Migrate MySQL 8.0 to Aurora 3? The Core Pain Points

Teams moving off Amazon RDS for MySQL 8.0 toward Aurora 3 usually hit the same three friction points:

1. Cost unpredictability — RDS bills for provisioned IOPS on top of instance hours. Aurora 3 bundles storage-tier I/O into the compute price.
2. Limits on scalability — MySQL 8.0 on RDS supports only one writer and up to 15 read replicas. Aurora 3 supports auto-scaling groups with zero-downtime failover.
3. Maintenance windows cause real business impact — Minor engine patches on RDS often restart instances; Aurora 3 applies patches across the cluster without downtime.

This guide answers the questions teams actually ask during a migration assessment.

MySQL 8.0 (RDS) vs. Aurora 3 — Side-by-Side Comparison

Factor	MySQL 8.0 on RDS	Aurora 3 (MySQL-Compatible)
Max read replicas	15	Up to 50 (Aurora Replicas)
Failover time	30–60 s (manual or promoted standby)	< 30 s automatic (DNS flip)
Storage scaling	Provisioned; must resize volumes	Auto-scales in 10 GB increments up to 128 TB
I/O pricing model	Per-provisioned IOPS + per-GB stored	Burstable included in compute tier
In-place upgrade path	N/A (target version)	Supported from MySQL 5.6 / 5.7 / 8.0
Parallel query engine	No (single-threaded optimizer)	Yes — distributed execution across vCPUs
Backtrack (point-in-time recovery)	Restore from snapshot (minutes–hours)	Native up to 6 h back in time, zero restore
Global databases (multi-region)	Not available natively	Yes — sub-second replication across regions
Approximate cost delta (m5.large → db.r6g.large equiv.)	$90–$140/mo instance + storage/IOPS	$120–$180/mo instance; storage billed separately but cheaper per-I/O

Migration Paths — Which One Fits Your Situation?

Path 1: DMS CDC Migration (Recommended for most workloads)

Use AWS Database Migration Service (DMS) with continuous replication. Steps:

1. Enable binary logging on MySQL 8.0 source (binlog_format = ROW).
2. Create an Aurora 3 target endpoint matching the source collation.
3. Run a full-load + CDC task; validate row counts before cutover.
4. Switch application endpoints during a scheduled maintenance window.

Path 2: Native Aurora 3 Upgrade (In-place)

For databases smaller than 2 TB where schema churn is low:

1. Take a snapshot of the existing RDS MySQL 8.0 instance.
2. Restore from snapshot into a new Aurora 3 cluster.
3. Run AWS Schema Conversion Tool to flag incompatible features (e.g., certain STORED PROCEDURE syntax changes).
4. Cutover when validation passes.

Path 3: Blue/Green Deployment (Zero-downtime)

Ideal for production environments that cannot accept any brief read outage:

1. Spin up a blue Aurora 3 environment alongside the green MySQL 8.0 RDS instance.
2. Replicate data continuously with DMS.
3. Switch the Application Load Balancer pointer once deltas reach zero.
4. Decommission the green environment after a 48-hour observation period.

Cost Optimization Checklist

Before you finalize your Aurora 3 deployment, verify each item below:

✓	Checklist Item	Why It Matters
☐	Right-size