不使用RDS用裸EC2实例部署MySQL：EBS存储下选I/D型实例是否有益？

Great question—this is a common point of confusion when picking EC2 instances for database workloads. Let’s break down whether I/D instances still make sense if you’re using EBS instead of their built-in instance storage:

Core Answer: Yes, they can still offer meaningful benefits #

Even if you ignore the included instance storage, I/D instances are purpose-built for storage-intensive workloads, which translates to several advantages for MySQL running on EBS:

• Tuned Hardware for I/O-Bound Workloads
  I/D instances come with CPU and memory configurations optimized for handling high disk I/O. This includes faster memory bandwidth, lower CPU latency for I/O operations, and kernel-level tweaks that prioritize disk-related tasks. For MySQL—where read/write latency directly impacts query performance—these optimizations can make a noticeable difference, even when the data lives on EBS.

• Higher EBS Performance Limits
  Most I/D instance types have significantly higher baseline EBS throughput and IOPS caps compared to general-purpose instances (like M5 or T3). For example, I3en instances support up to 20 Gbps of EBS bandwidth, which is way more than the 10 Gbps limit on M5 instances. If your MySQL workload involves large batch operations, frequent backups, or peak-time traffic, this extra EBS capacity prevents bottlenecks.

• Improved Network Performance
  I/D instances often include enhanced networking features—higher PPS (packets per second) rates, lower network latency, and dedicated network resources. This is critical if you’re using MySQL replication, read replicas, or need to sync data between instances regularly. Better network handling reduces overhead for database communication, keeping your queries responsive even under load.

• Potential Cost Efficiency
  Depending on your region and workload, I/D instances might offer a better price-to-performance ratio for I/O-heavy databases than general-purpose alternatives. If your MySQL setup is consistently pushing high I/O, the performance gains could justify the cost, even if you’re not using the local storage.

Things to Consider Before Choosing #

• Avoid Paying for Unused Resources
  Part of the I/D instance’s cost is tied to its built-in instance storage. If you’re 100% certain you’ll never need local storage (e.g., for temporary tables or caching), compare costs with similar instances that don’t include it. For example, an R5 instance might offer comparable CPU/memory/EBS specs at a lower price if you skip the local storage premium.

• Test with Your Actual Workload
  The only way to be sure is to run load tests with your specific MySQL workload. Spin up an I/D instance and a comparable general-purpose instance, then measure metrics like query latency, throughput, and resource utilization. This will tell you if the performance gains are worth the extra cost (if any) for your use case.

内容的提问来源于stack exchange，提问作者Arslan Mehboob