Chapter�3.營ntroduction to Amazon Elastic Compute Cloud

• Elastic—Amazon EC2 enables you to increase or decrease capacity within minutes, not hours or days. You can commission one, hundreds or even thousands of server instances simultaneously. Of course, because this is all controlled with web service APIs, your application can automatically scale itself up and down depending on its needs.

• Completely Controlled—You have complete control of your instances. You have root access to each one, and you can interact with them as you would any machine. Instances can be rebooted remotely using web service APIs. You also have access to console output of your instances.

• Flexible—You have the choice of several instance types, allowing you to select a configuration of memory, CPU, operating system, and instance storage that is optimal for your application.

• Designed for use with other Amazon Web Services—Amazon EC2 works in conjunction with Amazon Simple Storage Service (Amazon S3), Amazon SimpleDB and Amazon Simple Queue Service (Amazon SQS) to provide a complete solution for computing, query processing and storage across a wide range of applications.

• Reliable—Amazon EC2 offers a highly reliable environment where replacement instances can be rapidly and reliably commissioned. The service runs within Amazon’s proven network infrastructure and data centers.

• Multiple Locations—Amazon EC2 provides the ability to place instances in multiple locations. Amazon EC2 locations are composed of Regions and Availability Zones. Availability Zones are distinct locations that are engineered to be insulated from failures in other Availability Zones and provide inexpensive, low latency network connectivity to other Availability Zones in the same Region. By launching instances in separate Availability Zones, you can protect your applications from failure of a single location. Regions consist of one or more Availability Zones, are geographically dispersed, and will be in separate geographic areas or countries.

• Secure—Amazon EC2 provides web service interfaces to configure firewall settings that control network access to and between groups of instances.

• Inexpensive—Amazon EC2 passes on to you the financial benefits of Amazon’s scale. You pay a very low rate for the compute capacity you actually consume.

  • On-Demand Instances—On-Demand Instances let you pay for compute capacity by the hour with no long-term commitments. This frees you from the costs and complexities of planning, purchasing, and maintaining hardware and transforms what are commonly large fixed costs into much smaller variable costs. On-Demand Instances also remove the need to buy “safety net” capacity to handle periodic traffic spikes.

  • Reserved Instances—Reserved Instances give you the option to make a low, one-time payment for each instance you want to reserve and in turn receive a significant discount on the hourly usage charge for that instance. After the one-time payment for an instance, that instance is reserved for you, and you have no further obligation; you may choose to run that instance for the discounted usage rate for the duration of your term, or when you do not use the instance, you will not pay usage charges on it.

Features for Building Failure Resilient Applications

• Amazon Elastic Block Store—Amazon Elastic Block Store (Amazon EBS) offers persistent storage for Amazon EC2 instances. Amazon EBS volumes provide off-instance storage that persists independently from the life of an instance. Amazon EBS volumes are highly available, highly reliable volumes that can be attached to a running Amazon EC2 instance and are exposed as standard block devices. Amazon EBS volumes offer greatly improved durability over local Amazon EC2 instance stores, as Amazon EBS volumes are automatically replicated on the backend (in a single Availability Zone). For those wanting even more durability, Amazon EBS provides the ability to create point-in-time consistent snapshots of your volumes that are then stored in Amazon S3, and automatically replicated across multiple Availability Zones. These snapshots can be used as the starting point for new Amazon EBS volumes, and can protect your data for long term durability.

• Elastic IP Addresses—Elastic IP addresses are static IP addresses designed for dynamic cloud computing. An Elastic IP address is associated with your account not a particular instance, and you control that address until you choose to explicitly release it. Unlike traditional static IP addresses, however, Elastic IP addresses allow you to mask instance or Availability Zone failures by programmatically remapping your public IP addresses to any instance in your account. Rather than waiting on a data technician to reconfigure or replace your host, or waiting for DNS to propagate to all of your customers, Amazon EC2 enables you to engineer around problems with your instance or software by quickly remapping your Elastic IP address to a replacement instance.

• Auto Scaling—Auto Scaling offers the ability to automatically increase or decrease the number of running Amazon EC2 instances in response to your web application’s usage and the configuration you define. Auto Scaling makes it easy for you to optimize your Amazon EC2 usage, automatically scaling your cluster to ensure your application has the right number of instances running to meet your workload demands. Auto Scaling is particularly well suited for applications that experience hourly, daily, or weekly variability in usage.

• Elastic Load Balancing—Elastic Load Balancing offers the ability to evenly spread requests across your running Amazon EC2 instances. Unlike traditional load balancers or load balancing software, there is no need to provision, manage, or plan for load balancing capacity needs. Each Elastic Load Balancer is automatically scaled, fully fault-tolerant, and distributes incoming application traffic across a group of Amazon EC2 instances.

• Amazon CloudWatch—Amazon CloudWatch is a monitoring service for Amazon EC2 that is designed to gather, aggregate, store, and retrieve metrics. Amazon CloudWatch makes it easy to monitor your Amazon EC2 instances and aggregate metrics from instances like CPU or disk utilization over different time ranges and across different pools of resources. This service is tightly integrated with Amazon EC2’s Auto Scaling and Elastic Load Balancing, enabling you to use monitoring metrics to trigger scaling activities.

• Scalable Applications—You can build a scalable application that shrinks or expands to meet your current demands.

  This can help you use only the compute resources that you need and can help you respond to events where a mention on a popular news site can result in a dramatic spike in traffic.

• Temporary Events—You can use Amazon EC2 for temporary solutions and one-off events that would require you to maintain compute resources that are normally idle.

  This includes hosting conferences in virtual worlds, live blogging, distribution of newly released media, and short-term promotional web sites.

• Batch Processing—You can use Amazon EC2 for projects that require massive compute resources which would be expensive to build on your own.

  This includes video and image processing, financial data processing, and science and research applications.

• Fault Resilient Applications—You can build an application across multiple availability zones which will be protected against the loss of an entire physical location.