title: Which RDS instance type has better IO: Extra Large DB Instance or High-Memory Extra Large Instance
body: <p>I am getting IO performance concerns with Amazon RDS using mysql 5.5.12. There are 2 instance types that are similar and close in price:</p>
  
  <p>Extra Large DB Instance: 15 GB of memory, 8 ECUs (4 virtual cores with 2 ECUs each), 64-bit platform, High I/O Capacity (MySQL DB Engine Only) ($0.88 per hour)</p>
  
  <p>High-Memory Extra Large Instance 17.1 GB memory, 6.5 ECU (2 virtual cores with 3.25 ECUs each), 64-bit platform, High I/O Capacity ($0.65 per hour)</p>
  
  <p>Does anyone know if the Extra Large DB has faster IO than High-Memory Extra Large Instance?</p>