- Amazon started with S3 (Simple Storage Service) - purely storage service.
- For Computing purposes, Amazon started EC2
- EC2 allows hosting your application on virtual servers operated by Amazon, widely known as AWS.
- For calculating the availability as a resource, 1 compute unit at Amazon EC2 is roughly equivalent to a 1.2 GHz Xeon server.
- All computing resources are virtualized, none is physical. No physical details are ever published. However, the user has to manage his own file system. Based on need/request, disk space is mounted and is made available to the server. Further, it has to be managed by the application.
- There can be three types of instances,
- Large instances
Behavior on instances
- like a normal web server
- has a public web address
- Java Software available to convert command line instructions into SOAP wrapped API calls to AWS
- Need to download API tools from AWS
- Key pairs are tied to regions
- The benefit of this is that the servers are replicated across data centers located physically separately
- Allows scaling of servers based on need
- Consumes about 60-90 seconds to scale up based on the need (e.g. load on the server). If configured the appropriate way, the system will replicate the application code and launch new server instances within seconds to handle the extra load.
- Handles scaling up as well as down both at the same time. Automaticaly, the extra/unused instances will be shut down and released from the application deployment when there is no load to require their service.
- very useful in cases of spikes, specially high-peaks. New feature launches on sites, or sudden outbreak of news etc, cause spikes in server loads. At such times, AWS works perfectly to scale up the required computing power. The application owners are saved from buying extra servers for that 1 day load... :)
- Its possibel to say how many servers to add
- Such a scaling up/down can be configured. For example, it can be specifiied that request for new instances when current system's load exceeds 85% or scale down, when the usage goes below 20% used
- AMI = Amazon Machine Images
- EBS = Elastic Block Device
- Elastic IP = static ips assigned to instances
- Amazon EC2 = Amazon Elastic Computing Cloud