Amazon RDS on solid state drives

Question

I am planning to design a cloud based application which leverages the MySQL provided using Amazon RDS. I wish to setup read replicas for the data which I have obtained on solid state drives. Does Amazon RDS allow us to have instances using SSD's or we would have to use EBS with SSD support to achieve it ?

Answer 1

It is fully possible to create a RDS instance using SSD. However, it is not yet supported in CloudFormation to define a RDS resource that uses SSD (see others complaining about it here). Unfortunately I'm not able to find any information on when they're planning on supporting it in CloudFormation, but I hope it's soon! :)

Answer 2

AWS supports RDS Instances provisioned with SSD's either manually via the AWS Console or using a CloudFormation template to assign SSD storage to your RDS Instance when you spin it up, with a few caveats:

1. As of this writing, if you specify any DBSecurityGroups in your CloudFormation template, the StorageType attribute will be ignored
2. You CAN specify both a Security Group and a StorageType, but you'll have to use a VPC Security Group instead of a DBSecurityGroup

When first starting out, I'd suggest not worrying about the Provisioned IOPS (SSD) storage option unless you have significant data indicating your systems will require substantial I/O operations.

From the Documentation :

For more information about Amazon RDS and VPC, see Using Amazon RDS with Amazon VPC in the Amazon Relational Database Service User Guide.

If you already have your CloudFormation template defined to use a DBSecurityGroup, you may not be able to use an Update template to switch over to a VPC Security Group. You may have to re-launch your stack after updating the template to use a new VPC Security Group, which could cause either significant downtime or require extensive manual operations or automation development to mitigate the downtime risks.

In addition, if you specify this setting as a change to be applied in an CloudFormation Update Template, you may experience some interruptions on your RDS instance, so you should plan for potential downtime or service interruption accordingly.