RDS or SQL Azure, which one do you recommend?

Question

I have developed a web applicaiton that does soem heavy DB work. I have developed the application using ASP.net and SQL Server 2008 Express. I wanted to know which service I should use, Amazon RDS or SQL Azure. I can migrate to MySQL without a problem. SQL Azure costs about $10 (for what I need) and RD costs $89 all by default.

I also want to be able to easily scale the DB server up when needed. From what I've read, it's possible with RDS but not with SQL Azure. I mean it possible, but you need to configure your application to support the new architecture.

Another thing is fault tolerance. I've read that with Amazon RDS you don't have strong fault tolerance and you need to create another replica in case of hardware failure. With SQL Azure your are safe because by default the data is replicated across several data centers.

Which one I should go with. Am I missing something?

Answer 1

What's the heavy DB work? Select or DML? Any indication of user volume?

Wondering why you built your app on sql express if you it were going to migrating to something else.I don't know the entire details so I recommend neither of them.

I would recommend SQL server standard reserved instance if you can i.e $227/year + 0.05 / hour = 55.41 / month.

Mount an EBS volume for storage and you are good to go. First you should do some testing on sql express in ec2 instance and see if it can really handle your "heavy db work" with expected user volume.

If not get an instance with sql server standard.

Good luck with what decision you make.

Answer 2

The scaling depends on how you need to scale. SQL Azure is designed to provide good enough performance for typical loads, and if you need more than that then it's recommended that you shard your data across multiple databases (as these are spread across multiple servers). A lot more detail about it can be found on this technet article.

Regarding fault tolerance, SQL Azure replicates your data across multiple servers in the same datacentre so will still be susceptible if Microsoft manage to lose a whole datacentre.

Chances are if your database fits within the 1gb that $10/month provides then you won't have any problems with SQL Azure as the server will be able to keep the entire database in memory!