ArcGIS Server on Amazon EC2 - Introduction to Amazon terminology

Before you begin working with the Amazon platform, there are some new terms and concepts that are helpful to learn.

AWS Management Console

The AWS Management Console is Amazon's Web-based interface for managing your Amazon Elastic Compute Cloud (EC2) instances. This is where you configure your architecture in the cloud, adding instances, configuring load balancers, adding storage volumes, adjusting security, and so on.

The AWS Management Console requires you to log in with an account that you've set up with Amazon for the purpose of using its cloud. After a successful login, you can browse or search for the ArcGIS Server Amazon Machine Image (AMI) and use it to create EC2 instances (described further below).

Once you start creating EC2 instances, Amazon applies charges based on the amount of resources you use. The AWS Management Console allows you to view your account information and accumulated charges.

EC2 instance

An EC2 instance is a virtual machine that you create in EC2. You create the instance using an AMI that is preconfigured with Windows Server 2008 and ArcGIS software. The following AMIs are available:

ArcGIS Server AMI—Includes ArcGIS Server and ArcGIS Desktop
ArcGIS Enterprise Geodatabase AMI—Includes an enterprise geodatabase running on PostgreSQL

Once you create the instance, you can log into it using Windows Remote Desktop. If you've worked with ArcGIS Server before, this is where things start to look familiar. For example, once logged in to an instance with ArcGIS Server, you can use ArcGIS Server Manager or ArcCatalog to create and manage services.

EC2 instances can be stopped and started in much the same way you can shut down and start up a computer. Instances can also be terminated when they are no longer needed. Once you terminate an instance, all information about it is lost. For this reason, it's recommended that you store your data on Amazon Elastic Block Store (EBS) volumes attached to your instance and optionally back up your data using Amazon Simple Storage Service (S3).

Once you've created an instance, you'll add your own data, services, and other programs. Once you've configured your instance exactly the way you want, you can create a custom AMI reflecting your machine's current state. You can use the custom AMI to automatically create additional instances that scale out your deployment.

EBS volume

Amazon Elastic Block Store (EBS) volumes are virtual disk drives that you can attach to your EC2 instance to add more storage. The ArcGIS Server AMI creates a 100 GB EBS volume "GIS Data" and attaches it to the instance as the D: drive. A connection to this drive is preconfigured in ArcCatalog. Similarly, the Enterprise Geodatabase AMI comes with an attached 100 GB EBS volume to store the PostgreSQL cluster.

You can choose to place your data on these preattached volumes, or, if one of the volumes is the wrong size or unneeded, you can delete the volume and attach your own volume later.

If you create your own EBS volume, you must do the work of formatting the drive and attaching it (for example, you can configure it as drive E:). You can configure the drive to contain as much or as little space as you need.

EBS volumes are an excellent way to manage your data in the cloud independently from your software. For example, you can easily detach an EBS volume from one instance and attach it to another. When you terminate an instance, any previously attached EBS volumes are left behind, allowing you to attach them to other instances if desired.

You can create snapshots of your EBS volumes, which allow you to quickly generate identical volumes. Snapshots are useful if you need to share data across Amazon availability zones, or if you want to make the same data available to several Amazon accounts. Finally, snapshots provide a means of data backup; if a volume fails for some reason, you can deploy a new volume from the original snapshot without much loss.

Elastic Load Balancer

Amazon Elastic Load Balancers (ELBs) are a way to distribute work across multiple EC2 instances. All requests to your server go through the load balancer, which then evenly distributes the requests to the available EC2 instances. You can add or remove participating EC2 instances from the load balancer at any time.

Dive-in:

If you've worked with ArcGIS Server before, you may be accustomed to adding multiple server object containers (SOCs) to a server object manager (SOM) to scale out your deployment. To scale out on Amazon, you add multiple identical EC2 instances to an ELB. The SOM and SOC components still exist, but the SOM does not distribute requests to multiple SOC machines.

Regions and Availability Zones

Amazon EC2 consists of multiple data centers around the world that are designed to address enterprise architecture challenges.

Amazon Regions represent data center facilities in dispersed geographic locations such as the United States, Europe, and Asia.
Amazon Availability Zones are distinct locations within a region that are engineered to be isolated from failures in other Availability Zones. Configuring your application in multiple zones provides an extra layer of availability in case one of the zones should fail.

S3

Amazon Simple Storage Service (S3) is an Amazon service designed specifically for data storage in the cloud. This storage option has the lowest potential for data failure or loss. You can use S3 as a place for data backup or as a middle ground for data transfer between your on-premises deployment and your EBS volumes. Also, any snapshots you create of your EBS volumes are stored on S3.

1/30/2013