Amazon EC2 FAQs

Q: What is Amazon Elastic Compute Cloud (Amazon EC2)?

Amazon Elastic Compute Cloud (Amazon EC2) is a web service that provides resizable compute capacity in the cloud. It is designed to make web-scale computing easier for developers.

Q: What can I do with Amazon EC2?

Just as Amazon Simple Storage Service (Amazon S3) enables storage in the cloud, Amazon EC2 enables “compute” in the cloud. Amazon EC2’s simple web service interface allows you to obtain and configure capacity with minimal friction. It provides you with complete control of your computing resources and lets you run on Amazon’s proven computing environment. Amazon EC2 reduces the time required to obtain and boot new server instances to minutes, allowing you to quickly scale capacity, both up and down, as your computing requirements change. Amazon EC2 changes the economics of computing by allowing you to pay only for capacity that you actually use.

Q: How can I get started with Amazon EC2?

To sign up for Amazon EC2, click the “Sign up for This Web Service” button on the Amazon EC2 detail page. You must have an Amazon Web Services account to access this service; if you do not already have one, you will be prompted to create one when you begin the Amazon EC2 sign-up process. After signing up, please refer to the Amazon EC2 documentation, which includes our Getting Started Guide.

Q: Why am I asked to verify my phone number when signing up for Amazon EC2?

Amazon EC2 registration requires you to have a valid phone number and email address on file with AWS in case we ever need to contact you. Verifying your phone number takes only a couple of minutes and involves receiving a phone call during the registration process and entering a PIN number using the phone key pad.

Q: What can developers now do that they could not before?

Until now, small developers did not have the capital to acquire massive compute resources and ensure they had the capacity they needed to handle unexpected spikes in load. Amazon EC2 enables any developer to leverage Amazon’s own benefits of massive scale with no up-front investment or performance compromises. Developers are now free to innovate knowing that no matter how successful their businesses become, it will be inexpensive and simple to ensure they have the compute capacity they need to meet their business requirements.

The “Elastic” nature of the service allows developers to instantly scale to meet spikes in traffic or demand. When computing requirements unexpectedly change (up or down), Amazon EC2 can instantly respond, meaning that developers have the ability to control how many resources are in use at any given point in time. In contrast, traditional hosting services generally provide a fixed number of resources for a fixed amount of time, meaning that users have a limited ability to easily respond when their usage is rapidly changing, unpredictable, or is known to experience large peaks at various intervals.

Q: How do I run systems in the Amazon EC2 environment?

Once you have set up your account and select or create your AMIs, you are ready to boot your instance. You can start your AMI on any number of On-Demand instances by using the RunInstances API call. You simply need to indicate how many instances you wish to launch. If you wish to run more than 20 On-Demand instances, complete the Amazon EC2 instance request form.

If Amazon EC2 is able to fulfill your request, RunInstances will return success, and we will start launching your instances. You can check on the status of your instances using the DescribeInstances API call. You can also programmatically terminate any number of your instances using the TerminateInstances API call.

If you have a running instance using an Amazon EBS boot partition, you can also use the StopInstances API call to release the compute resources but preserve the data on the boot partition. You can use the StartInstances API when you are ready to restart the associated instance with the Amazon EBS boot partition.

In addition, you have the option to use Spot Instances to reduce your computing costs when you have flexibility in when your applications can run. Read more about Spot Instances for a more detailed explanation on how Spot Instances work.

If you prefer, you can also perform all these actions from the AWS Management Console or through the command line using our command line tools, which have been implemented with this web service API.

Q: What is the difference between using the local instance store and Amazon Elastic Block Store (Amazon EBS) for the root device?

When you launch your Amazon EC2 instances you have the ability to store your root device data on Amazon EBS or the local instance store. By using Amazon EBS, data on the root device will persist independently from the lifetime of the instance. This enables you to stop and restart the instance at a subsequent time, which is similar to shutting down your laptop and restarting it when you need it again.

Alternatively, the local instance store only persists during the life of the instance. This is an inexpensive way to launch instances where data is not stored to the root device. For example, some customers use this option to run large web sites where each instance is a clone to handle web traffic.

Q: How quickly will systems be running?

It typically takes less than 10 minutes from the issue of the RunInstances call to the point where all requested instances begin their boot sequences. This time depends on a number of factors including: the size of your AMI, the number of instances you are launching, and how recently you have launched that AMI. Images launched for the first time may take slightly longer to boot.

Q: How do I load and store my systems with Amazon EC2?

Amazon EC2 allows you to set up and configure everything about your instances from your operating system up to your applications. An Amazon Machine Image (AMI) is simply a packaged-up environment that includes all the necessary bits to set up and boot your instance. Your AMIs are your unit of deployment. You might have just one AMI or you might compose your system out of several building block AMIs (e.g., webservers, appservers, and databases). Amazon EC2 provides a number of tools to make creating an AMI easy. Once you create a custom AMI, you will need to bundle it. If you are bundling an image with a root device backed by Amazon EBS, you can simply use the bundle command in the AWS Management Console. If you are bundling an image with a boot partition on the instance store, then you will need to use the AMI Tools to upload it to Amazon S3. Amazon EC2 uses Amazon EBS and Amazon S3 to provide reliable, scalable storage of your AMIs so that we can boot them when you ask us to do so.

Or, if you want, you don’t have to set up your own AMI from scratch. You can choose from a number of globally available AMIs that provide useful instances. For example, if you just want a simple Linux server, you can choose one of the standard Linux distribution AMIs.

Q: How do I access my systems?

The RunInstances call that initiates execution of your application stack will return a set of DNS names, one for each system that is being booted. This name can be used to access the system exactly as you would if it were in your own data center. You own that machine while your operating system stack is executing on it.

Q: Is Amazon EC2 used in conjunction with Amazon S3?

Yes, Amazon EC2 is used jointly with Amazon S3 for instances with root devices backed by local instance storage. By using Amazon S3, developers have access to the same highly scalable, reliable, fast, inexpensive data storage infrastructure that Amazon uses to run its own global network of web sites. In order to execute systems in the Amazon EC2 environment, developers use the tools provided to load their AMIs into Amazon S3 and to move them between Amazon S3 and Amazon EC2. See How do I load and store my systems with Amazon EC2? for more information about AMIs.

We expect developers to find the combination of Amazon EC2 and Amazon S3 to be very useful. Amazon EC2 provides cheap, scalable compute in the cloud while Amazon S3 allows users to store their data reliably.

Q: How many instances can I run in Amazon EC2?

You are limited to running up to a total of 20 On-Demand instances across the instance family, purchasing 20 Reserved Instances, and requesting Spot Instances per your dynamic Spot limit per region. New AWS accounts may start with limits that are lower than the limits described here. Certain instance types are further limited per region as follows:

Note that cc2.8xlarge, hs1.8xlarge, cr1.8xlarge, G2, D2, and I2 instances are not available in all regions.

If you need more instances, complete the Amazon EC2 instance request form with your use case and your instance increase will be considered. Limit increases are tied to the region they were requested for.

Q: Are there any limitations in sending email from Amazon EC2 instances?

Yes. In order to maintain the quality of Amazon EC2 addresses for sending email, we enforce default limits on the amount of email that can be sent from EC2 accounts. If you wish to send larger amounts of email from EC2, you can apply to have these limits removed from your account by filling out this form.

Q: How quickly can I scale my capacity both up and down?

Amazon EC2 provides a truly elastic computing environment. 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. When you need more instances, you simply call RunInstances, and Amazon EC2 will typically set up your new instances in a matter of minutes. Of course, because this is all controlled with web service APIs, your application can automatically scale itself up and down depending on its needs.

Q: What operating system environments are supported?

Amazon EC2 currently supports a variety of operating systems including: Amazon Linux, Ubuntu, Windows Server, Red Hat Enterprise Linux, SUSE Linux Enterprise Server, Fedora, Debian, CentOS, Gentoo Linux, Oracle Linux, and FreeBSD. We are looking for ways to expand it to other platforms.

Q: Does Amazon EC2 use ECC memory?

In our experience, ECC memory is necessary for server infrastructure, and all the hardware underlying Amazon EC2 uses ECC memory.

Q: How is this service different than a plain hosting service?

Traditional hosting services generally provide a pre-configured resource for a fixed amount of time and at a predetermined cost. Amazon EC2 differs fundamentally in the flexibility, control and significant cost savings it offers developers, allowing them to treat Amazon EC2 as their own personal data center with the benefit of Amazon.com’s robust infrastructure.

When computing requirements unexpectedly change (up or down), Amazon EC2 can instantly respond, meaning that developers have the ability to control how many resources are in use at any given point in time. In contrast, traditional hosting services generally provide a fixed number of resources for a fixed amount of time, meaning that users have a limited ability to easily respond when their usage is rapidly changing, unpredictable, or is known to experience large peaks at various intervals.

Secondly, many hosting services don’t provide full control over the compute resources being provided. Using Amazon EC2, developers can choose not only to initiate or shut down instances at any time, they can completely customize the configuration of their instances to suit their needs – and change it at any time. Most hosting services cater more towards groups of users with similar system requirements, and so offer limited ability to change these.

Finally, with Amazon EC2 developers enjoy the benefit of paying only for their actual resource consumption – and at very low rates. Most hosting services require users to pay a fixed, up-front fee irrespective of their actual computing power used, and so users risk overbuying resources to compensate for the inability to quickly scale up resources within a short time frame.

Q: How will I be charged and billed for my use of Amazon EC2?

You pay only for what you use. Displayed pricing is an hourly rate but depending on which instances you choose, you pay by the hour or second (minimum of 60 seconds) for each instance type. Partial instance-hours consumed are billed based on instance usage. Data transferred between AWS services in different regions will be charged as Internet Data Transfer on both sides of the transfer. Usage for other Amazon Web Services is billed separately from Amazon EC2.

For EC2 pricing information, please visit the pricing section on the EC2 detail page.

Q: When does billing of my Amazon EC2 systems begin and end?

Billing commences when Amazon EC2 initiates the boot sequence of an AMI instance. Billing ends when the instance terminates, which could occur through a web services command, by running "shutdown -h", or through instance failure. When you stop an instance, we shut it down but don't charge hourly usage for a stopped instance, or data transfer fees, but we do charge for the storage for any Amazon EBS volumes. To learn more, visit the AWS Documentation.

Q: What defines billable EC2 instance usage?

Instance usages are billed for any time your instances are in a "running" state. If you no longer wish to be charged for your instance, you must "stop" or "terminate" the instance to avoid being billed for additional instance usage. Billing starts when an instance transitions into the running state.

Q: If I have two instances in different availability zones, how will I be charged for regional data transfer?

Each instance is charged for its data in and data out at corresponding Data Transfer rates. Therefore, if data is transferred between these two instances, it is charged at "Data Transfer Out from EC2 to Another AWS Region" for the first instance and at "Data Transfer In from Another AWS Region" for the second instance. Please refer to this page for detailed data transfer.

Q. If I have two instances in different regions, how will I be charged for data transfer?

Each instance is charged for its data in and data out at Internet Data Transfer rates. Therefore, if data is transferred between these two instances, it is charged at Internet Data Transfer Out for the first instance and at Internet Data Transfer In for the second instance.

Q: How will my monthly bill show per-second versus per-hour?

Although EC2 charges in your monthly bill will now be calculated based on a per second basis, for consistency, the monthly EC2 bill will show cumulative usage for each instance that ran in a given month in decimal hours. An example would be an instance running for 1 hour 10 minutes and 4 seconds would look like 1.1677. Read this blog for an example of the detailed billing report.

Q: Do your prices include taxes?

Except as otherwise noted, our prices are exclusive of applicable taxes and duties, including VAT and applicable sales tax. For customers with a Japanese billing address, use of AWS services is subject to Japanese Consumption Tax. Learn more.

Q: What kind of hardware will my application stack run on?

Visit Amazon EC2 Instance Type for a list of EC2 instances available by region.

Q: How do I select the right instance type?

Amazon EC2 instances are grouped into 5 families: General Purpose, Compute Optimized, Memory Optimized, Storage Optimized and Accelerated Computing instances. General Purpose Instances have memory to CPU ratios suitable for most general purpose applications and come with fixed performance (M5, M4) or burstable performance (T2); Compute Optimized instances (C5, C4) have proportionally more CPU resources than memory (RAM) and are well suited for scale out compute-intensive applications and High Performance Computing (HPC) workloads; Memory Optimized Instances (X1e, X1, R4) offer larger memory sizes for memory-intensive applications, including database and memory caching applications; Accelerating Computing instances (P3, P2, G3, F1) take advantage of the parallel processing capabilities of NVIDIA Tesla GPUs for high performance computing and machine/deep learning; GPU Graphics instances (G3) offer high-performance 3D graphics capabilities for applications using OpenGL and DirectX; F1 instances deliver Xilinx FPGA-based reconfigurable computing; Storage Optimized Instances (H1, I3, D2) that provide very high, low latency, I/O capacity using SSD-based local instance storage for I/O-intensive applications, with D2 or H1, the dense-storage and HDD-storage instances, provide local high storage density and sequential I/O performance for data warehousing, Hadoop and other data-intensive applications. When choosing instance types, you should consider the characteristics of your application with regards to resource utilization (i.e. CPU, Memory, Storage) and select the optimal instance family and instance size.

Q: What is an “EC2 Compute Unit” and why did you introduce it?

Transitioning to a utility computing model fundamentally changes how developers have been trained to think about CPU resources. Instead of purchasing or leasing a particular processor to use for several months or years, you are renting capacity by the hour. Because Amazon EC2 is built on commodity hardware, over time there may be several different types of physical hardware underlying EC2 instances. Our goal is to provide a consistent amount of CPU capacity no matter what the actual underlying hardware.

Amazon EC2 uses a variety of measures to provide each instance with a consistent and predictable amount of CPU capacity. In order to make it easy for developers to compare CPU capacity between different instance types, we have defined an Amazon EC2 Compute Unit. The amount of CPU that is allocated to a particular instance is expressed in terms of these EC2 Compute Units. We use several benchmarks and tests to manage the consistency and predictability of the performance from an EC2 Compute Unit. The EC2 Compute Unit (ECU) provides the relative measure of the integer processing power of an Amazon EC2 instance. Over time, we may add or substitute measures that go into the definition of an EC2 Compute Unit, if we find metrics that will give you a clearer picture of compute capacity.

Q: What is the regional availability of Amazon EC2 instance types?
For a list of all instances and regional availability, visit Amazon EC2 Pricing.

Q: How do I prevent other people from viewing my systems?

You have complete control over the visibility of your systems. The Amazon EC2 security systems allow you to place your running instances into arbitrary groups of your choice. Using the web services interface, you can then specify which groups may communicate with which other groups, and also which IP subnets on the Internet may talk to which groups. This allows you to control access to your instances in our highly dynamic environment. Of course, you should also secure your instance as you would any other server.

Q: Can I get a history of all EC2 API calls made on my account for security analysis and operational troubleshooting purposes?

Yes. To receive a history of all EC2 API calls (including VPC and EBS) made on your account, you simply turn on CloudTrail in the AWS Management Console.  For more information, visit the CloudTrail home page. 

Q: Where can I find more information about security on AWS?

For more information on security on AWS please refer to our Amazon Web Services: Overview of Security Processes white paper and to our Amazon EC2 running Windows Security Guide.

Q: Why am I limited to 5 Elastic IP addresses per region?

Public (IPV4) internet addresses are a scarce resource. There is only a limited amount of public IP space available, and Amazon EC2 is committed to helping use that space efficiently.

By default, all accounts are limited to 5 Elastic IP addresses per region. If you need more the 5 Elastic IP addresses, we ask that you apply for your limit to be raised. We will ask you to think through your use case and help us understand your need for additional addresses. You can apply for more Elastic IP address here. Any increases will be specific to the region they have been requested for.

Q: Why am I charged when my Elastic IP address is not associated with a running instance?

In order to help ensure our customers are efficiently using the Elastic IP addresses, we impose a small hourly charge for each address when it is not associated to a running instance.

Q: Do I need one Elastic IP address for every instance that I have running?

No. You do not need an Elastic IP address for all your instances. By default, every instance comes with a private IP address and an internet routable public IP address. The private IP address remains associated with the network interface when the instance is stopped and restarted, and is released when the instance is terminated. The public address is associated exclusively with the instance until it is stopped, terminated or replaced with an Elastic IP address. These IP addresses should be adequate for many applications where you do not need a long lived internet routable end point. Compute clusters, web crawling, and backend services are all examples of applications that typically do not require Elastic IP addresses.

Q: How long does it take to remap an Elastic IP address?

The remap process currently takes several minutes from when you instruct us to remap the Elastic IP until it fully propagates through our system.

Q: Can I configure the reverse DNS record for my Elastic IP address?

Yes, you can configure the reverse DNS record of your Elastic IP address by filling out this form. Note that a corresponding forward DNS record pointing to that Elastic IP address must exist before we can create the reverse DNS record.

Q: How isolated are Availability Zones from one another?

Each Availability Zone runs on its own physically distinct, independent infrastructure, and is engineered to be highly reliable. Common points of failures like generators and cooling equipment are not shared across Availability Zones. Additionally, they are physically separate, such that even extremely uncommon disasters such as fires, tornados or flooding would only affect a single Availability Zone.

Q: Is Amazon EC2 running in more than one region?

Yes. Please refer to Regional Products and Services for more details of our product and service availability by region.

Q: How can I make sure that I am in the same Availability Zone as another developer?

We do not currently support the ability to coordinate launches into the same Availability Zone across AWS developer accounts. One Availability Zone name (for example, us-east-1a) in two AWS customer accounts may relate to different physical Availability Zones.

Q: If I transfer data between Availability Zones using public IP addresses, will I be charged twice for Regional Data Transfer (once because it’s across zones, and a second time because I’m using public IP addresses)?

No. Regional Data Transfer rates apply if at least one of the following is true, but is only charged once for a given instance even if both are true:

• The other instance is in a different Availability Zone, regardless of which type of address is used.
• Public or Elastic IP addresses are used, regardless of which Availability Zone the other instance is in.
  

Q. What is the Nitro Hypervisor?

The launch of C5 instances introduced a new hypervisor for Amazon EC2, the Nitro Hypervisor. As a component of the Nitro system, the Nitro Hypervisor primarily provides CPU and memory isolation for EC2 instances. VPC networking and EBS storage resources are implemented by dedicated hardware components, Nitro Cards that are part of all current generation EC2 instance families. The Nitro Hypervisor is built on core Linux Kernel-based Virtual Machine (KVM) technology, but does not include general-purpose operating system components.

Q. How does the Nitro Hypervisor benefit customers?

The Nitro Hypervisor provides consistent performance and increased compute and memory resources for EC2 virtualized instances by removing host system software components. It allows AWS to offer larger instance sizes (like c5.18xlarge) that provide practically all of the resources from the server to customers. Previously, C3 and C4 instances each eliminated software components by moving VPC and EBS functionality to hardware designed and built by AWS. This hardware enables the Nitro Hypervisor to be very small and uninvolved in data processing tasks for networking and storage.

Q. Will all EC2 instances use the Nitro Hypervisor?

Eventually all new instance types will use the Nitro Hypervisor, but in the near term, some new instance types will use Xen depending on the requirements of the platform.

Q. Will AWS continue to invest in its Xen-based hypervisor?

Yes. As AWS expands its global cloud infrastructure, EC2’s use of its Xen-based hypervisor will also continue to grow. Xen will remain a core component of EC2 instances for the foreseeable future. AWS is a founding member of the Xen Project since its establishment as a Linux Foundation Collaborative Project and remains an active participant on its Advisory Board. As AWS expands its global cloud infrastructure, EC2’s Xen-based hypervisor also continues to grow. Therefore EC2’s investment in Xen continues to grow, not shrink

Q. How many EBS volumes and Elastic Network Interfaces (ENIs) can be attached to instances running on the Nitro Hypervisor?

Instances running on the Nitro Hypervisor support a maximum of 27 additional PCI devices for EBS volumes and VPC ENIs. Each EBS volume or VPC ENI uses a PCI device. For example, if you attach 3 additional network interfaces to an instance that uses the Nitro Hypervisor, you can attach up to 24 EBS volumes to that instance.

Q. Will the Nitro Hypervisor change the APIs used to interact with EC2 instances?

No, all the public facing APIs for interacting with EC2 instances that run using the Nitro Hypervisor will remain the same. For example, the “hypervisor” field of the DescribeInstances response, which will continue to report “xen” for all EC2 instances, even those running under the Nitro Hypervisor. This field may be removed in a future revision of the EC2 API.

Q. Which AMIs are supported on instances that use the Nitro Hypervisor?

EBS backed HVM AMIs with support for ENA networking and booting from NVMe storage can be used with instances that run under the Nitro Hypervisor. The latest Amazon Linux AMI and Windows AMIs provided by Amazon are supported, as are the latest AMI of Ubuntu, Debian, Red Hat Enterprise Linux, SUSE Enterprise Linux, CentOS, and FreeBSD.

Q. Will I notice any difference between instances using Xen hypervisor and those using the Nitro Hypervisor?

Yes. For example, instances running under the Nitro Hypervisor boot from EBS volumes using an NVMe interface. Instances running under Xen boot from an emulated IDE hard drive, and switch to the Xen paravirtualized block device drivers.

Operating systems can identify when they are running under a hypervisor. Some software assumes that EC2 instances will run under the Xen hypervisor and rely on this detection. Operating systems will detect they are running under KVM when an instance uses the Nitro Hypervisor, so the process to identify EC2 instances should be used to identify EC2 instances that run under both hypervisors.

All the features of EC2 such as Instance Metadata Service work the same way on instances running under both Xen and the Nitro Hypervisor. The majority of applications will function the same way under both Xen and the Nitro Hypervisor as long as the operating system has the needed support for ENA networking and NVMe storage.

Q. How are instance reboot and termination EC2 API requests implemented by the Nitro Hypervisor?

The Nitro Hypervisor signals the operating system running in the instance that it should shut down cleanly by industry standard ACPI methods. For Linux instances, this requires that acpid be installed and functioning correctly. If acpid is not functioning in the instance, termination events will be delayed by multiple minutes and will then execute as a hard reset or power off.

Q. How do EBS volumes behave when accessed by NVMe interfaces?

There are some important differences in how operating system NVMe drivers behave compared to Xen paravirtual (PV) block drivers.

First, the NVMe device names used by Linux based operating systems will be different than the parameters for EBS volume attachment requests and block device mapping entries such as /dev/xvda and /dev/xvdf. NVMe devices are enumerated by the operating system as /dev/nvme0n1, /dev/nvme1n1, and so on. The NVMe device names are not persistent mappings to volumes, therefore other methods like file system UUIDs or labels should be used when configuring the automatic mounting of file systems or other startup activities. When EBS volumes are accessed via the NVMe interface, the EBS volume ID is available via the controller serial number and the device name specified in EC2 API requests is provided by an NVMe vendor extension to the Identify Controller command. This enables backward compatible symbolic links to be created by a utility script. For more information see the EC2 documentation on device naming and NVMe based EBS volumes.

Second, by default the NVMe drivers included in most operating systems implement an I/O timeout. If an I/O does not complete in an implementation specific amount of time, usually tens of seconds, the driver will attempt to cancel the I/O, retry it, or return an error to the component that issued the I/O. The Xen PV block device interface does not time out I/O, which can result in processes that cannot be terminated if it is waiting for I/O. The Linux NVMe driver behavior can be modified by specifying a higher value for the nvme.io timeout kernel module parameter.

Third, the NVMe interface can transfer much larger amounts of data per I/O, and in some cases may be able to support more outstanding I/O requests, compared to the Xen PV block interface. This can cause higher I/O latency if very large I/Os or a large number of I/O requests are issued to volumes designed to support throughput workloads like EBS Throughput Optimized HDD (st1) and Cold HDD (sc1) volumes. This I/O latency is normal for throughput optimized volumes in these scenarios, but may cause I/O timeouts in NVMe drivers. The I/O timeout can be adjusted in the Linux driver by specifying a larger value for the nvme_core.io_timeout kernel module parameter.

Q: What networking capabilities are included in this feature?

We currently support enhanced networking capabilities using SR-IOV (Single Root I/O Virtualization). SR-IOV is a method of device virtualization that provides higher I/O performance and lower CPU utilization compared to traditional implementations. For supported Amazon EC2 instances, this feature provides higher packet per second (PPS) performance, lower inter-instance latencies, and very low network jitter.

Q: Why should I use Enhanced Networking?

If your applications benefit from high packet-per-second performance and/or low latency networking, Enhanced Networking will provide significantly improved performance, consistence of performance and scalability.

Q: How can I enable Enhanced Networking on supported instances?

In order to enable this feature, you must launch an HVM AMI with the appropriate drivers. C5, C5d, F1, G3, H1, I3, m4.16xlarge, M5, M5d, P2, P3, R4, R5, R5d, T3, X1, X1e, and z1d instances use the Elastic Network Adapter (which uses the “ena” Linux driver) for Enhanced Networking. C3, C4, D2, I2, M4 (excluding m4.16xlarge), and R3 instances use Intel® 82599g Virtual Function Interface (which uses the “ixgbevf” Linux driver). Amazon Linux AMI includes both of these drivers by default. For AMIs that do not contain these drivers, you will need to download and install the appropriate drivers based on the instance types you plan to use. You can use Linux or Windows instructions to enable Enhanced Networking in AMIs that do not include the SR-IOV driver by default. Enhanced Networking is only supported in Amazon VPC.

Q: Do I need to pay an additional fee to use Enhanced Networking?

No, there is no additional fee for Enhanced Networking. To take advantage of Enhanced Networking you need to launch the appropriate AMI on a supported instance type in a VPC.

Q: Why is Enhanced Networking only supported in Amazon VPC?

Amazon VPC allows us to deliver many advanced networking features to you that are not possible in EC2-Classic. Enhanced Networking is another example of a capability enabled by Amazon VPC.

Q: Which instance types support Enhanced Networking?

Depending on your instance type, enhanced networking can be enabled using one of the following mechanisms:

Intel 82599 Virtual Function (VF) interface - The Intel 82599 Virtual Function interface supports network speeds of up to 10 Gbps for supported instance types. C3, C4, D2, I2, M4 (excluding m4.16xlarge), and R3 instances use the Intel 82599 VF interface for enhanced networking.

Elastic Network Adapter (ENA) - The Elastic Network Adapter (ENA) supports network speeds of up to 25 Gbps for supported instance types. C5, C5d, F1, G3, H1, I3, m4.16xlarge, M5, M5d, P2, P3, R4, R5, R5d, T3, X1, X1e, and z1d instances use the Elastic Network Adapter for enhanced networking.

Q. Which instance types offer NVMe instance storage?

High I/O instances use NVMe based local instance storage to deliver very high, low latency, I/O capacity to applications, and are optimized for applications that require millions of IOPS. Like Cluster instances, High I/O instances can be clustered via cluster placement groups for high bandwidth networking.

Q: What happens to my data when a system terminates?

The data stored on a local instance store will persist only as long as that instance is alive. However, data that is stored on an Amazon EBS volume will persist independently of the life of the instance. Therefore, we recommend that you use the local instance store for temporary data and, for data requiring a higher level of durability, we recommend using Amazon EBS volumes or backing up the data to Amazon S3. If you are using an Amazon EBS volume as a root partition, you will need to set the Delete On Terminate flag to "N" if you want your Amazon EBS volume to persist outside the life of the instance.

Q: What kind of performance can I expect from Amazon EBS volumes?

Amazon EBS provides four current generation volume types and are divided into two major categories: SSD-backed storage for transactional workloads and HDD-backed storage for throughput intensive workloads. These volume types differ in performance characteristics and price, allowing you to tailor your storage performance and cost to the needs of your applications. For more information on see the EBS product details page, and for additional information on performance, see the Amazon EC2 User Guide's EBS Performance section.

Q: What are Throughput Optimized HDD (st1) and Cold HDD (sc1) volume types?

ST1 volumes are backed by hard disk drives (HDDs) and are ideal for frequently accessed, throughput intensive workloads with large datasets and large I/O sizes, such as MapReduce, Kafka, log processing, data warehouse, and ETL workloads. These volumes deliver performance in terms of throughput, measured in MB/s, and include the ability to burst up to 250 MB/s per TB, with a baseline throughput of 40 MB/s per TB and a maximum throughput of 500 MB/s per volume. ST1 is designed to deliver the expected throughput performance 99% of the time and has enough I/O credits to support a full-volume scan at the burst rate.

SC1 volumes are backed by hard disk drives (HDDs) and provides the lowest cost per GB of all EBS volume types. It is ideal for less frequently accessed workloads with large, cold datasets. Similar to st1, sc1 provides a burst model: these volumes can burst up to 80 MB/s per TB, with a baseline throughput of 12 MB/s per TB and a maximum throughput of 250 MB/s per volume. For infrequently accessed data, sc1 provides extremely inexpensive storage. SC1 is designed to deliver the expected throughput performance 99% of the time and has enough I/O credits to support a full-volume scan at the burst rate.

To maximize the performance of st1 and sc1, we recommend using EBS-optimized EC2 instances.

Q: Which volume type should I choose?

Amazon EBS includes two major categories of storage: SSD-backed storage for transactional workloads (performance depends primarily on IOPS) and HDD-backed storage for throughput workloads (performance depends primarily on throughput, measured in MB/s). SSD-backed volumes are designed for transactional, IOPS-intensive database workloads, boot volumes, and workloads that require high IOPS. SSD-backed volumes include Provisioned IOPS SSD (io1) and General Purpose SSD (gp2). HDD-backed volumes are designed for throughput-intensive and big-data workloads, large I/O sizes, and sequential I/O patterns. HDD-backed volumes include Throughput Optimized HDD (st1) and Cold HDD (sc1). For more information on Amazon EBS see the EBS product details page.

Q: Do you support multiple instances accessing a single volume?

While you are able to attach multiple volumes to a single instance, attaching multiple instances to one volume is not supported at this time.

Q: Will I be able to access my EBS snapshots using the regular Amazon S3 APIs?

No, EBS snapshots are only available through the Amazon EC2 APIs.

Q: Do volumes need to be un-mounted in order to take a snapshot? Does the snapshot need to complete before the volume can be used again? 

No, snapshots can be done in real time while the volume is attached and in use. However, snapshots only capture data that has been written to your Amazon EBS volume, which might exclude any data that has been locally cached by your application or OS. In order to ensure consistent snapshots on volumes attached to an instance, we recommend cleanly detaching the volume, issuing the snapshot command, and then reattaching the volume. For Amazon EBS volumes that serve as root devices, we recommend shutting down the machine to take a clean snapshot.

Q: Are snapshots versioned? Can I read an older snapshot to do a point-in-time recovery?

Each snapshot is given a unique identifier, and customers can create volumes based on any of their existing snapshots.

Q: What charges apply when using Amazon EBS shared snapshots?

If you share a snapshot, you won’t be charged when other users make a copy of your snapshot. If you make a copy of another user’s shared volume, you will be charged normal EBS rates.

Q: Can users of my Amazon EBS shared snapshots change any of my data?

Users who have permission to create volumes based on your shared snapshots will first make a copy of the snapshot into their account. Users can modify their own copies of the data, but the data on your original snapshot and any other volumes created by other users from your original snapshot will remain unmodified.

Q: How can I discover Amazon EBS snapshots that have been shared with me?

You can find snapshots that have been shared with you by selecting “Private Snapshots” from the viewing dropdown in the Snapshots section of the AWS Management Console. This section will list both snapshots you own and snapshots that have been shared with you.

Q: How can I find what Amazon EBS snapshots are shared globally?

You can find snapshots that have been shared globally by selecting “Public Snapshots” from the viewing dropdown in the Snapshots section of the AWS Management Console.

Q: Do you offer encryption on Amazon EBS volumes and snapshots?

Yes. EBS offers seamless encryption of data volumes and snapshots. EBS encryption better enables you to meet security and encryption compliance requirements.

Q: How can I find a list of Amazon Public Data Sets?

All information on Public Data Sets is available in our Public Data Sets Resource Center. You can also obtain a listing of Public Data Sets within the AWS Management Console by choosing “Amazon Snapshots” from the viewing dropdown in the Snapshots section.

Q: Where can I learn more about EBS?

You can visit the Amazon EBS FAQ page.

Q. How do I access a file system from an Amazon EC2 instance?

To access your file system, you mount the file system on an Amazon EC2 Linux-based instance using the standard Linux mount command and the file system’s DNS name. Once you’ve mounted, you can work with the files and directories in your file system just like you would with a local file system.

Amazon EFS uses the NFSv4.1 protocol. For a step-by-step example of how to access a file system from an Amazon EC2 instance, please see the Amazon EFS Getting Started guide.

Q. What Amazon EC2 instance types and AMIs work with Amazon EFS?

Amazon EFS is compatible with all Amazon EC2 instance types and is accessible from Linux-based AMIs. You can mix and match the instance types connected to a single file system. For a step-by-step example of how to access a file system from an Amazon EC2 instance, please see the Amazon EFS Getting Started guide.

Q. How do I load data into a file system?

You can load data into an Amazon EFS file system from your Amazon EC2 instances or from your on-premises datacenter servers.

Amazon EFS file systems can be mounted on an Amazon EC2 instance, so any data that is accessible to an Amazon EC2 instance can also be read and written to Amazon EFS. To load data that is not currently stored on the Amazon cloud, you can use the same methods you use to transfer files to Amazon EC2 today, such as Secure Copy (SCP).

Amazon EFS file systems can also be mounted on an on-premises server, so any data that is accessible to an on-premises server can be read and written to Amazon EFS using standard Linux tools. For more information about accessing a file system from an on-premises server, please see the On-premises Access section of the Amazon EFS FAQ.

For more information about moving data to the Amazon cloud, please see the Cloud Data Migration page.

Q. How do I access my file system from outside my VPC?

Amazon EC2 instances within your VPC can access your file system directly, and Amazon EC2 Classic instances outside your VPC can mount a file system via ClassicLink. On-premises servers can mount your file systems via an AWS Direct Connect connection to your VPC.

Q. How many Amazon EC2 instances can connect to a file system?

Amazon EFS supports one to thousands of Amazon EC2 instances connecting to a file system concurrently.

Q: Where can I learn more about EFS?

You can visit the Amazon EFS FAQ page.

Q: What is the minimum time interval granularity for the data that Amazon CloudWatch receives and aggregates?

Metrics are received and aggregated at 1 minute intervals.

Q: Which operating systems does Amazon CloudWatch support?

Amazon CloudWatch receives and provides metrics for all Amazon EC2 instances and should work with any operating system currently supported by the Amazon EC2 service.

Q: Will I lose the metrics data if I disable monitoring for an Amazon EC2 instance?

You can retrieve metrics data for any Amazon EC2 instance up to 2 weeks from the time you started to monitor it. After 2 weeks, metrics data for an Amazon EC2 instance will not be available if monitoring was disabled for that Amazon EC2 instance. If you want to archive metrics beyond 2 weeks you can do so by calling mon-get-stats command from the command line and storing the results in Amazon S3 or Amazon SimpleDB.

Q: Can I access the metrics data for a terminated Amazon EC2 instance or a deleted Elastic Load Balancer?

Yes. Amazon CloudWatch stores metrics for terminated Amazon EC2 instances or deleted Elastic Load Balancers for 2 weeks.

Q: Does the Amazon CloudWatch monitoring charge change depending on which type of Amazon EC2 instance I monitor?

No, the Amazon CloudWatch monitoring charge does not vary by Amazon EC2 instance type.

Q: Why does the graphing of the same time window look different when I view in 5 minute and 1 minute periods?

If you view the same time window in a 5 minute period versus a 1 minute period, you may see that data points are displayed in different places on the graph. For the period you specify in your graph, Amazon CloudWatch will find all the available data points and calculates a single, aggregate point to represent the entire period. In the case of a 5 minute period, the single data point is placed at the beginning of the 5 minute time window. In the case of a 1 minute period, the single data point is placed at the 1 minute mark. We recommend using a 1 minute period for troubleshooting and other activities that require the most precise graphing of time periods.

Q: Can I automatically scale my Amazon EC2 fleets?

Yes. Amazon EC2 Auto Scaling is a fully managed service designed to launch or terminate Amazon EC2 instances automatically to help ensure you have the correct number of Amazon EC2 instances available to handle the load for your application. EC2 Auto Scaling helps you maintain application availability through fleet management for EC2 instances, which detects and replaces unhealthy instances, and by scaling your Amazon EC2 capacity up or down automatically according to conditions you define. You can use EC2 Auto Scaling to automatically increase the number of Amazon EC2 instances during demand spikes to maintain performance and decrease capacity during lulls to reduce costs. For more information see the Amazon EC2 Auto Scaling FAQ.

Q: What load balancing options does the Elastic Load Balancing service offer?

Elastic Load Balancing offers two types of load balancers that both feature high availability, automatic scaling, and robust security. These include the Classic Load Balancer that routes traffic based on either application or network level information, and the Application Load Balancer that routes traffic based on advanced application level information that includes the content of the request.

Q: When should I use the Classic Load Balancer and when should I use the Application Load Balancer?

The Classic Load Balancer is ideal for simple load balancing of traffic across multiple EC2 instances, while the Application Load Balancer is ideal for applications needing advanced routing capabilities, microservices, and container-based architectures. Please visit Elastic Load Balancing for more information.

Q: What is a Reserved Instance?

A Reserved Instance (RI) is an EC2 offering that provides you with a significant discount on EC2 usage when you commit to a one-year or three-year term.

Q: What are the differences between Standard RIs and Convertible RIs?

Standard RIs offer a significant discount on EC2 instance usage when you commit to a particular instance family. Convertible RIs offer you the option to change your instance configuration during the term, and still receive a discount on your EC2 usage. For more information on Convertible RIs, please click here.

Q: Do RIs provide a capacity reservation?

Yes, when a Standard or Convertible RI is scoped to a specific Availability Zone (AZ), instance capacity matching the exact RI configuration is reserved for your use (these are referred to as “zonal RIs”). Zonal RIs give you additional confidence in your ability to launch instances when you need them.

You can also choose to forego the capacity reservation and purchase Standard or Convertible RIs that are scoped to a region (referred to as “regional RIs”). Regional RIs automatically apply the discount to usage across Availability Zones and instance sizes in a region, making it easier for you to take advantage of the RI’s discounted rate.

Q: When should I purchase a zonal RI?

If you want to take advantage of the capacity reservation, then you should buy an RI in a specific Availability Zone.

Q: When should I purchase a regional RI?

If you do not require the capacity reservation, then you should buy a regional RI. Regional RIs provide AZ and instance size flexibility, which offers broader applicability of the RI’s discounted rate.

Q: What are Availability Zone and instance size flexibility?

Availability Zone and instance size flexibility make it easier for you to take advantage of your regional RI’s discounted rate. Availability Zone flexibility applies your RI’s discounted rate to usage in any Availability Zone in a region, while instance size flexibility applies your RI’s discounted rate to usage of any size within an instance family. Let’s say you own an m5.2xlarge Linux/Unix regional RI with default tenancy in US East (N.Virginia). Then this RI’s discounted rate can automatically apply to two m5.xlarge instances in us-east-1a or four m5.large instances in us-east-1b.

Q: What types of RIs provide instance size flexibility?

Linux/Unix regional RIs with the default tenancy provide instance size flexibility. Instance size flexibility is not available on RIs of other platforms such as Windows, Windows with SQL Standard, Windows with SQL Server Enterprise, Windows with SQL Server Web, RHEL, and SLES.

Q: Do I need to take any action to take advantage of Availability Zone and instance size flexibility?

Regional RIs do not require any action to take advantage of Availability Zone and instance size flexibility.

Q: I own zonal RIs how do I assign them to a region?

You can assign your Standard zonal RIs to a region by modifying the scope of the RI from a specific Availability Zone to a region from the EC2 management console or by using the ModifyReservedInstances API. 

Q: How do I purchase an RI?

To get started, you can purchase an RI from the EC2 Management Console or by using the AWS CLI. Simply specify the instance type, platform, tenancy, term, payment option, and region or Availability Zone.

Q: Can I purchase an RI for a running instance?

Yes, AWS will automatically apply an RI’s discounted rate to any applicable instance usage from the time of purchase. Visit the Getting Started page to learn more.

Q: Can I control which instances are billed at the discounted rate?

No. AWS automatically optimizes which instances are charged at the discounted rate to ensure you always pay the lowest amount. For information about billing, and how it applies to RIs, see Billing Benefits and Payment Options.

Q: How does instance size flexibility work?

EC2 uses the scale shown below, to compare different sizes within an instance family. In the case of instance size flexibility on RIs, this scale is used to apply the discounted rate of RIs to the normalized usage of the instance family. For example, if you have an m5.2xlarge RI that is scoped to a region, then your discounted rate could apply towards the usage of 1 m5.2xlarge or 2 m5.xlarge instances.

Click here to learn more about how instance size flexibility of RIs applies to your EC2 usage. And click here to learn about how instance size flexibility of RIs is presented in the Cost and Usage Report.