I am plannig to port an e-exam app on the aws cloud. I have decided to use a ELB, EC2 instances. But i am confused on wether to use a MYSQL DB server on amazon instance or to go for amazon RDS?
Also what if my loadbalancer fails?
What if I configure my HttpServer as loadbalancer?(and what if this also fails)
How can I use EBS effectively?
Please guide me. I am totally new to this concept.
thanx n regards :)
Advantages of using the Amazon RDS: They manage it for you (back-ups, mirroring, etc) Biggest Disadvantage for using the Amazon RDS: The potential cost of having them run the server for you 24/7. If you have the money for the added cost of them managing a MySQL server for you then I would say go for it. If you feel comfortable with managing a MySQL server and you can wrap everything onto one EC2 (possibly problematic) it would be cost effective to do it this way. Alternatively, look into the Simple DB system and see if it works for you. If you have no need for a full relation DB system and seeing relatively light DB load it may be advantageous.
If your loadbalancer fails, it can be really crappy. In all likelihood you will lose the assigned address. But the loadbalancer "should" come back by itself. However, I have heard of people having a load balancer running under load for over a year without problem. There are quite a few tutorials out there on how to setup a webserver up as a proxy/loadbalancer.
Effective use of the EBS depends on the specifics of your application. EBS volumes are easy and quick to create/mount/dispose of. You can create and mount them dynamically. There are SDKs for manipulating most every element of AWS written in pretty much every common language. Personally, I am using the AWS SDK for PHP and it works very well. There are also a number of command line utilities to use with shell scripts. http://docs.amazonwebservices.com/AWSSDKforPHP/latest/index.html is the documentation for that. Otherwise, look through the AWS Developer tools for other languages/utilities.
Brian answered much of your query. My only point to add is that you are best off to start small and then build out your infrastructure. With cloud you only pay for what you use, which is a great opportunity to test things without any upfront commitment to build load balancers, scalable databases, automatic scaling etc.
So just deploy everything on one box using all the technologies you are familiar with, and then start to bring in RDS and loadbalancers. You may actually realize that you don't like the concept of RDP and that the loadbalancers offered by default have too many quirks to meet your business requirements.
