Amazon EC2 Instance Types

† AVX, AVX2, and Enhanced Networking are only available on instances launched with HVM AMIs.

Amazon EC2 instances provide a number of additional features to help you deploy, manage, and scale your applications.

Amazon EC2 allows you to choose between Fixed Performance Instances (e.g. M3, C3, and R3) and Burstable Performance Instances (e.g. T2). Burstable Performance Instances provide a baseline level of CPU performance with the ability to burst above the baseline.

T2 Unlimited instances can sustain high CPU performance for as long as a workload needs it. For most general-purpose workloads, T2 Unlimited instances will provide ample performance without any additional charges. The hourly T2 instance price automatically covers all interim spikes in usage when the average CPU utilization of a T2 instance is at or less than the baseline over a 24-hour window. If the instance needs to run at higher CPU utilization for a prolonged period, it can do so at a flat additional charge of 5 cents per vCPU-hour.

T2 instances’ baseline performance and ability to burst are governed by CPU Credits. Each T2 instance receives CPU Credits continuously, the rate of which depends on the instance size. T2 instances accrue CPU Credits when they are idle, and use CPU credits when they are active. A CPU Credit provides the performance of a full CPU core for one minute.

For example, a t2.small instance receives credits continuously at a rate of 12 CPU Credits per hour. This capability provides baseline performance equivalent to 20% of a CPU core (20% x 60 mins = 12 mins). If the instance does not use the credits it receives, they are stored in its CPU Credit balance up to a maximum of 288 CPU Credits. When the t2.small instance needs to burst to more than 20% of a core, it draws from its CPU Credit balance to handle this surge automatically.

With T2 Unlimited enabled, the t2.small instance can burst above the baseline even after its CPU Credit balance is drawn down to zero. For a vast majority of general purpose workloads where the average CPU utilization is at or below the baseline performance, the basic hourly price for t2.small covers all CPU bursts. If the instance happens to run at an average 25% CPU utilization (5% above baseline) over a period of 24 hours after its CPU Credit balance is drawn to zero, it will be charged an additional 6 cents (5 cents/vCPU-hour x 1 vCPU x 5% x 24 hours).

Many applications such as web servers, developer environments and small databases don’t need consistently high levels of CPU, but benefit significantly from having full access to very fast CPUs when they need them. T2 instances are engineered specifically for these use cases. If you need consistently high CPU performance for applications such as video encoding, high volume websites or HPC applications, we recommend you use Fixed Performance Instances. T2 instances are designed to perform as if they have dedicated high speed Intel cores available when your application really needs CPU performance, while protecting you from the variable performance or other common side-effects you might typically see from over-subscription in other environments.

Amazon EC2 allows you to choose between multiple storage options based on your requirements. Amazon EBS is a durable, block-level storage volume that you can attach to a single, running Amazon EC2 instance. You can use Amazon EBS as a primary storage device for data that requires frequent and granular updates. For example, Amazon EBS is the recommended storage option when you run a database on Amazon EC2. Amazon EBS volumes persist independently from the running life of an Amazon EC2 instance. Once a volume is attached to an instance you can use it like any other physical hard drive. Amazon EBS provides three volume types to best meet the needs of your workloads: General Purpose (SSD), Provisioned IOPS (SSD), and Magnetic. General Purpose (SSD) is the new, SSD-backed, general purpose EBS volume type that we recommend as the default choice for customers. General Purpose (SSD) volumes are suitable for a broad range of workloads, including small to medium sized databases, development and test environments, and boot volumes. Provisioned IOPS (SSD) volumes offer storage with consistent and low-latency performance, and are designed for I/O intensive applications such as large relational or NoSQL databases. Magnetic volumes provide the lowest cost per gigabyte of all EBS volume types. Magnetic volumes are ideal for workloads where data is accessed infrequently, and applications where the lowest storage cost is important.

Many Amazon EC2 instances can also include storage from disks that are physically attached to the host computer. This disk storage is referred to as instance store. Instance store provides temporary block-level storage for Amazon EC2 instances. The data on an instance store volume persists only during the life of the associated Amazon EC2 instance.

In addition to block level storage via Amazon EBS or instance store, you can also use Amazon S3 for highly durable, highly available object storage. Learn more about Amazon EC2 storage options from the Amazon EC2 documentation.

For an additional, low, hourly fee, customers can launch selected Amazon EC2 instances types as EBS-optimized instances. For C5, C4, M5, M4, P3, P2, G3, and D2 instances, this feature is enabled by default at no additional cost. EBS-optimized instances enable EC2 instances to fully use the IOPS provisioned on an EBS volume. EBS-optimized instances deliver dedicated throughput between Amazon EC2 and Amazon EBS, with options between 500 and 4,000 Megabits per second (Mbps) depending on the instance type used. The dedicated throughput minimizes contention between Amazon EBS I/O and other traffic from your EC2 instance, providing the best performance for your EBS volumes. EBS-optimized instances are designed for use with both Standard and Provisioned IOPS Amazon EBS volumes. When attached to EBS-optimized instances, Provisioned IOPS volumes can achieve single digit millisecond latencies and are designed to deliver within 10% of the provisioned IOPS performance 99.9% of the time. We recommend using Provisioned IOPS volumes with EBS-optimized instances or instances that support cluster networking for applications with high storage I/O requirements.

Select EC2 instances support cluster networking when launched into a common cluster placement group. A cluster placement group provides low-latency networking between all instances in the cluster. The bandwidth an EC2 instance can utilize depends on the instance type and its networking performance specification. Inter instance traffic within the same region can utilize up to 5 Gbps for single-flow and up to 25 Gbps for multi-flow traffic in each direction (full duplex). Traffic to and from S3 buckets in the same region can also utilize all available instance aggregate bandwidth. When launched in a placement group, instances can utilize up to 10 Gbps for single-flow traffic and up to 25 Gbps for multi-flow traffic. Network traffic to the Internet is limited to 5 Gbps (full duplex). Cluster networking is ideal for high performance analytics systems and many science and engineering applications, especially those using the MPI library standard for parallel programming.

Amazon EC2 allows you to provision a variety of instances types, which provide different combinations of CPU, memory, disk, and networking. Launching new instances and running tests in parallel is easy, and we recommend measuring the performance of applications to identify appropriate instance types and validate application architecture. We also recommend rigorous load/scale testing to ensure that your applications can scale as you intend.

Amazon EC2 provides you with a large number of options across ten different instance types, each with one or more size options, organized into six distinct instance families optimized for different types of applications. We recommend that you assess the requirements of your applications and select the appropriate instance family as a starting point for application performance testing. You should start evaluating the performance of your applications by (a) identifying how your application needs compare to different instance families (e.g. is the application compute-bound, memory-bound, etc.?), and (b) sizing your workload to identify the appropriate instance size. There is no substitute for measuring the performance of your full application since application performance can be impacted by the underlying infrastructure or by software and architectural limitations. We recommend application-level testing, including the use of application profiling and load testing tools and services.