Placing Spot Requests

The Spot Instance request (or bid) is a core element in Amazon EC2 Spot Instances. Your specifications for a Spot request—price, Availability Zone, launch group, and schedule—affect the fulfillment of the request and the successful launch of Spot Instances.

This section discusses the bid fundamentals you need to know to help you manage your Spot requests.

Depending on how quickly you want your Spot request fulfilled and how long you want your Spot Instances to continue running, there are a number of factors you need to consider when you bid on Spot Instances. The requirements you include in your Spot request can affect the chances that it will be fulfilled. If you have a number of requirements that must be met, your request can take longer to fulfill.

The maximum Spot Instance price you're willing to pay—your bid price—may also affect how long your Spot Instances will run. If you want your instances to run as long as possible and have a low probability of interruption, you might consider submitting a higher bid price. If you are less concerned about Spot interruptions and simply want to take advantage of Spot cost savings, you should submit a lower bid price.

Your bid price is not necessarily the price that you pay. For example, if you bid $0.500, and the Spot price is $0.300 per hour for the period, you only pay $0.300 per hour. If the Spot price drops, you pay less. If the Spot price increases, you pay the new price up to your bid price. If the Spot price rises above your bid price (or another capacity constraint is encountered), your Spot Instance is interrupted.