AWS maven I'm not

June 5, 2014 8:32 AM

A question for folks knowledgeable about Amazon Web Services...is it better to have EC2 and RDS is the same Availability Zone?

I run a web app in an AWS EC2 instance and the database for the app in an RDS instance both in Amazon Web Services Region East-1. However, one of them is in Availability Zone 1a and the other is in 1d. Am I getting all the speed benefits of having both instances in the same "data center" (East-1) even if they are in different Availability Zones, or can I get further optimization by moving them to the same Availability Zone?

A second question is whether there would be any drawbacks that I'm not thinking about (aside from cost) to using in EC2 a managed web server from the AWS Marketplace such as NGINX Plus from Nginx, Inc. if I have a need for a managed/supported web server due to lack of in-house management resources. (For that same reason, I am 1) not installing MySQL in EC2, and 2) not thinking of using an unmanaged hosting service such as Linode or Digital Ocean - I have developers developing and implementing the app but they would probably not be the right resource to manage ongoing regular maintenance, only major issues).

Any other related tips and suggestions about using AWS are welcome.

Thank you.

posted by Dansaman to Technology (1 answer total)

I think the main disadvantage to having them in different availability zones is that your app will stop working if either AZ 1a OR 1d goes down. If they're both in the same AZ, only that one AZ would effect its uptime, essentially halving the risk. If high availability is a requirement, you should have redundant app servers and database servers in multiple AZs, so that if one AZ goes down you wouldn't suffer any downtime.

I've observed about 33% greater inter-zone latency compared to intra-zone, but both are sub-1ms, so you might get a very slight performance improvement if both are in the same AZ.
posted by Emanuel at 9:56 AM on June 5, 2014