How many instances can I launch?

Each user has a concurrent running instance limit. For new users, this limit is 20. If you need more than 20 instances, please complete the Amazon EC2 Instance Request Form and your request will be considered.

How do I sign a request?

Information on signing SOAP requests is provided in Request Authentication . Information on signing Query requests is provided in Query API Authentication .

What username do I use for the various Amazon EC2 tools?

When you sign up with Amazon Web Services, you are provided an AWS Account ID. This is your username. For more information, refer to the Amazon Elastic Compute Cloud Getting Started Guide.

Why do my instances take so long to start?

Amazon EC2 must move the images around the network before they can be launched. For big images and/or congested networks, this can take several minutes. To improve performance, images are cached. As you launch your images more frequently, it should be less noticeable.

How durable are the instance stores?

Instance stores appear to an instance as a local disk. They will survive intentional and unintentional reboots of the instance unless the instance terminates or the underlying drive fails.

You should always backup or replicate important data.

What happens to my running instances if the machines on which they are running go down?

The instances will terminate and will need to be relaunched. The data on the instances' hard drives will be lost.

Always replicate important data or store it in Amazon S3.

Can I get a bigger/smaller/differently optimized virtual machine?

Yes. For more information, see Instance Types.

Is there a REST interface to Amazon EC2?

Not at present. You can use the SOAP API, Query API, or the command line tools.

How does Amazon EC2 handle load balancing?

With a service as flexible as Amazon EC2, you can use many types of load balancing systems. The load balancing instances can forward traffic to other systems. There are several open source solutions that are in wide use.

Does Amazon perform system maintenance?

Yes. Periodically, Amazon might perform maintenance that requires a reboot of your system. Make sure your instances can recover and restart after being rebooted.