Understand RDS scalability

[Rumman]

Hi,

In the following question

28. QUESTION

Category: CSAA – Design Resilient Architectures

A company has recently adopted a hybrid cloud architecture and is planning to migrate a database hosted on-premises to AWS. The database currently has over 50 TB of consumer data, handles highly transactional (OLTP) workloads, and is expected to grow. The Solutions Architect should ensure that the database is ACID-compliant and can handle complex queries of the application.

Which type of database service should the Architect use?

RDS is given as a wrong answer because Amazon RDS is incorrect. Although this service can host an ACID-compliant relational database that can handle complex queries and transactional (OLTP) workloads, it is still not scalable to handle the growth of the database. Amazon Aurora is the better choice as its underlying storage can grow automatically as needed.

However, on the AWS website, they say

“With RDS Storage Auto Scaling, you simply set your desired maximum storage limit, and Auto Scaling takes care of the rest.

RDS Storage Auto Scaling continuously monitors actual storage consumption, and scales capacity up automatically when actual utilization approaches provisioned storage capacity. Auto Scaling works with new and existing database instances. You can enable Auto Scaling with just a few clicks in the AWS Management Console. There is no additional cost for RDS Storage Auto Scaling.“

So I am wondering what it is meant here as the DB is not scalable? Secondly, isn’t Aurora already part of RDS as well?

[Caloy]

• This reply was modified 3 years, 4 months ago by  Caloy.

[Carlo-TutorialsDojo]

Hello Rumman,

Thank you for bringing this up to our attention. I concur with your point that technically, Aurora is part of Amazon RDS, albeit there are some differences between these two database services. Aurora started out as a MySQL and PostgreSQL-compatible relational database engine option for Amazon RDS. Today, it has various features that you won’t see in RDS, such as Aurora Serverless and Amazon Aurora machine learning to name a few.

A few years ago, Amazon S3 and Amazon Glacier were actually two different services but now, Glacier is called “Amazon S3 Glacier” and is considered as part of Amazon S3. This is quite confusing since Amazon S3 Glacier still uses its old Glacier Console that is separate from the S3 Console. This is related to what’s happening here between RDS and Aurora.

Using RDS “could be” the same thing as using Aurora, but definitely NOT entirely.

For example, in this scenario, the application requires an OLTP database (e.g. MySQL) to migrate their on-premises database that has 50 TB of consumer data. You have two options:

1. Go to the RDS Console and launch an Amazon Aurora database with MySQL compatibility

2. Go to the RDS Console and launch an Amazon RDS for MySQL database

For Aurora, it automatically grows as the amount of data in your database increases. However, in RDS, you still have to manually set the maximum storage threshold. Currently, in RDS, the maximum value is 65,536 GiB which is roughly equivalent to 65 TB. Storage Auto Scaling in RDS is not enabled by default, unlike Aurora. Take note that it is stated in the scenario that the database currently has 50 TB of consumer data and is expected to grow.

I hope this answers your question.

Let us know if you need further assistance. The Tutorials Dojo team is dedicated to helping you pass your AWS exam on your first try!

Regards,

Carlo @ TutorialsDojo