December 2009 Archives

Today we launched a new option for acquiring Amazon EC2 Compute resources: Spot Instances. Using this option, customers bid any price they like on unused Amazon EC2 capacity and run those instances for as long their bid exceeds the current "Spot Price." Spot Instances are ideal for tasks that can be flexible as to when they start and stop. This gives our customers an exciting new approach to IT cost management.

The central concept in this new option is that of the Spot Price, which we determine based on current supply and demand and will fluctuate periodically. If the maximum price a customer has bid exceeds the current Spot Price then their instances will be run, priced at the current Spot Price. If the Spot Price rises above the customer's bid, their instances will be terminated and restarted (if the customer wants it restarted at all) when the Spot Price falls below the customer's bid. This gives customers exact control over the maximum cost they are incurring for their workloads, and often will provide them with substantial savings. It is important to note that customers will pay only the existing Spot Price; the maximum price just specifies how much a customer is willing to pay for capacity as the Spot Price changes.

Spot Instances are ideal for Amazon EC2 customers who have workloads that are flexible as to when its tasks are run. These can be incidental tasks, such as the analysis of a particular dataset, or tasks where the amount of work to be done is almost never finished, such as media conversion from a Hollywood's studio's movie vault, or web crawling for a search indexing company. For most of these tasks their completion is not time critical and as such they are ideal targets for additional cost savings.

Economies of scale

Spot Instances are an innovation that is made possible by the unparalleled economies of scale created by the tremendous growth of the AWS Infrastructure Services. The broad Amazon EC2 customer base brings such diversity in workload and utilization patterns that it allows us to operate Amazon EC2 with extreme efficiency. True to the Amazon philosophy, we let our customers benefit from the economies of scale they help us create by lowering our prices when we achieve lower cost structures. Consistently we have lowered compute, storage and bandwidth prices based on such cost savings.

This massive scale also enables new innovative purchasing models such as Spot Instances that empower our customers to gain even more control over the cost-effectiveness of their IT infrastructure. A highly efficient purchasing model such as Spot Instances is another way in which Amazon EC2 customers benefit from the unique economies of scale found in AWS Infrastructure Services.

Different Purchasing Models

The three different purchasing models Amazon EC2 offers give customers maximum flexibility in managing their IT costs; On-Demand Instances are charged by the hour at a fixed rate with no commitment; with Reserved Instances you pay a low, one-time fee and in turn receive a significant discount on the hourly usage charge for that instance; and Spot Instances provide the ability to assign the maximum price you want for capacity with flexible start and end times.

• On-Demand Instances - On-Demand Instances let you pay for compute capacity by the hour with no long-term commitments or upfront payments. You can increase or decrease your compute capacity depending on the demands of your application and only pay the specified hourly rate for the instances you use. These instances are used mostly for short term workloads and for workloads with unpredictable resource demand characteristics.
• Reserved Instances - Reserved Instances let you make a low, one-time, upfront payment for an instance, reserve it for a one or three year term, and pay a significantly lower rate for each hour you run that instance. You are assured that your Reserved Instance will always be available in the Availability Zone in which you purchased it. These instances are used for longer running workloads with predictable resource demands.
• Spot Instances - Spot Instances allow you to specify the maximum hourly price that you are willing to pay to run a particular instance type. We set a Spot Price for each instance type in each region, which is the price all customers will pay to run a Spot Instance for that given hour. The Spot Price fluctuates based on supply and demand for instances, but customers will never pay more than the maximum price they have specified. These instances are used for workloads with flexible completion times.

Managing Spot Instance Applications

There is one technological requirement for the applications that run as Spot Instances: they need to be able to handle that their computation can be stopped and restarted based on the Spot Price in relation to the customer's pricing limit. Ideally these applications will periodically save their state into, for example, EBS or Amazon S3 and upon restart read the last saved state and continue their work. This snapshot-restart technique is a well known methodology already available to many batch oriented applications.

There are three features that help customers manage their Spot Instances and the pricing.

• Persistent Requests: Spot Instance requests can be one-time or persistent. A one-time request will only be satisfied once; a persistent request will remain in consideration after each instance termination. A persistent request is useful when you have a large amount of computing that you want to get done but only below a certain price. By using a persistent request, customers can launch instances any time the Spot Price is below the target price and steadily work through the tasks.
• Launch Groups and specifying Availability Zones: Customers can request a cluster of instances to always launch and terminate simultaneously by specifying a Launch Group. They can also specify the Availability Zone these Instances should be launched in.
• Price History: Amazon EC2 provides a history of the Spot Price for each instance type in each Region via the AWS Management Console and the APIs. Spot Price history is a valuable tool in helping customers use what-if scenarios to determine right pricing level for a particular workload.

Spot instances are a great innovation that, as far as I know, has no equivalent in the IT industry. It brings our customers a powerful new way of managing the cost for those workloads that are flexible in their execution and completion times. This new customer-managed pricing approach holds the power to make new areas of computing feasible for which the economics were previously unfavorable.

For more details and background information visit the Amazon EC2 Spot Instance detail page, the AWS developer blog and the good folks at RightScale.

Today a powerful new feature is available for our Amazon EC2 customers: the ability to boot their instances from Amazon EBS (Elastic Block Store).

Customers like the simplicity of the AMI (Amazon Machine Image) model where they either choose a preconfigured AMI or upload their own AMI into Amazon S3. A wide variety of operating systems and software configurations is available for use. But customers have also asked us for more flexibility and control in the way that Amazon EC2 instances are booted such that they have finer grained control over for example what software configurations and data sets are available to the instance at boot time.

The ability to boot from Amazon EBS gives customers very powerful control over the boot configuration of the Amazon EC2 instances. In the traditional boot process, the root partition of the image will be the local disk, which is created and populated at boot time. In the new Amazon EBS boot process, the root partition is an Amazon EBS volume, which is created at boot time from an Amazon EBS snapshot. Other Amazon EBS volumes beyond the root disk can also made part of the instance before it is booted. This allows for a very fine-grain control of software and data configuration. An additional advantage of using the Amazon EBS boot process is that root partitions are no longer constrained by the size of the local disk and can be up to 1TB in size. And the new boot process is significantly faster because a local disk no longer needs to be populated.

With this new boot process another powerful feature is available to our Amazon EC2 customers: the ability to stop an instance and restart it at a later time with the disk configuration intact. When an instance is restarted, the customer can choose to use a different instance type (e.g., with more memory or CPU), a different operating system (e.g., with new security patches installed), or add new user data. While the instance is stopped it does not accrue any usage hours and customers are only charged for the storage associated with the Amazon EBS volume. The ability to stop and restart an instance is a very powerful mechanism that makes management of instances much easier; many scenarios related to adaptive instance sizing and software management have now become much simpler.

The new boot from Amazon EBS feature is an important step in our continuing quest to remove more and more of the heavy lifting that comes with today's computer environments.

For more details on the new boot features visit the Amazon EC2 detail page and the posting on the AWS developer blog. RightScale's perspective is also worth reading.

We have expanded the AWS footprint in the US and starting today a new AWS Region is available for use: US-West (Northern California). This new Region consists of multiple Availability Zones and provides low-latency access to the AWS services from for example the Bay Area. In the US, AWS customers now can choose between the US-East (Northern Virginia) Region and the new US-West (Northern California) Region. In addition, the EU (Ireland) Region is available to customers who want local access to services from Europe to address their performance or jurisdiction requirements.

As we announced earlier this month a Region with multiple Availability Zones will come online in Singapore in the first half of 2010, with other regions in Asia to follow later in 2010.

AWS is committed to making its services available at low cost. We use the cost-following principle in pricing the services and several times we have lowered our pricing in response to the cost savings we were able to achieve. Operation costs are often different based on location and, as such, the pricing for services may vary somewhat between Regions, giving our customers the power to make trade-offs between, for example, cost and latency.