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1.    EBS are network attached storages thus it will consume your network bandwidth to connect the the volumes, so if you have a network intensive application on your EC2 instance it might affect the connection between your instance to your EBS volumes. Optimized instances are just instances with a "dedicated" connection to EBS volumes, that means that you will have a dedicated amount of bandwidth just for your EBS volumes. Each instance has a limit of bandwidth for their connections to the EBS volumes.  

2.    To obtain additional, dedicated capacity for Amazon EBS I/O, you can launch some instance types as EBS–optimized instances (Bandwidth between EC2 instance and EBS volumes). Some instance types are EBS–optimized by default. 

3.    To maximize the networking and bandwidth performance of your instance type, you can do the following:

·         Launch supported instance types into a placement group: Instances in a common placement group can benefit from high-bandwidth (10 Gbps), low-latency networking.  Instance types that support 10 Gbps network speeds can only take advantage of those network speeds when launched in a placement group.

·         Enable enhanced networking for supported current generation instance types to get significantly higher packet per second (PPS) performance, lower network jitter, and lower latencies.

4.    T2 instances are lowest cost instance type, with a burstable CPU.

5.    T2 instances are designed to provide moderate baseline performance (minimum CPU all time) and the capability to burst to significantly higher performance as required by your workload. They are intended for workloads that don't use the full CPU often or consistently, but occasionally need to burst. T2 instances are well suited for general purpose workloads, such as web servers, developer environments, and small databases. 

6.    You must launch your T2 instances using an EBS volume as the root device.

7.    T2 instances are available as On-Demand instances and Reserved Instances, but they are not available as Spot instances, Scheduled Instances, or Dedicated instances. They are also not supported on a Dedicated Host.

8.    There is a limit on the total number of instances that you can launch in a region, and there are additional limits on some instance types. 

9.    C4 instances are ideal for compute-bound applications that benefit from high performance processors. C4 instances are well suited for the following applications:

·         Batch processing workloads

·         Media transcoding

·         High-traffic web servers, massively multiplayer online (MMO) gaming servers, and ad serving engines

·         High performance computing (HPC) and other compute-intensive applications

10. C4 instances are EBS-optimized by default, and deliver dedicated block storage throughput to Amazon EBS ranging from 500 Mbps to 4,000 Mbps at no additional cost. EBS-optimized instances enable you to get consistently high performance for your EBS volumes by eliminating contention between Amazon EBS I/O and other network traffic from your C4 instance. 

11. You can cluster C4 instances in a placement group. Placement groups provide low latency and high-bandwidth connectivity between the instances within a single Availability Zone

12. Accelerated computing instance families use hardware accelerators, or co-processors, to perform some functions, such as floating point number calculation and graphics processing, more efficiently than is possible in software running on CPUs.

13. I2 instances are optimized to deliver tens of thousands of low-latency, random I/O operations per second (IOPS) to applications. They are well suited for the following scenarios:

·         NoSQL databases (for example, Cassandra and MongoDB)

·         Clustered databases

·         Online transaction processing (OLTP) systems

14. I2 Instance Features

·         The primary data storage is SSD-based instance storage. Like all instance storage, these volumes persist only for the life of the instance. 

15. D2 instances are designed for workloads that require high sequential read and write access to very large data sets on local storage. D2 instances are well suited for the following applications:

·         Massive parallel processing (MPP) data warehouse

·         MapReduce and Hadoop distributed computing

·         Log or data processing applications

16. The primary data storage for D2 instances is HDD-based instance storage.

17. EC2-VPC, the private IP is retained but public is released and Elastic IP addresses are also retained.

18. for EC2-Classic instances, public and private IP addresses are released when the instance is stopped, new addresses are assigned when restarted and the Elastic IP addresses are disassociated

19. Because Amazon EC2 instance store-backed AMIs can’t be stopped, they’re either running or terminated. 

20. If the root device for your instance is an EBS volume, you can change the size of the instance simply by changing its instance type, which is known as resizing it (Changing the instance type)

21. Important Points about re-sizing :

a.    While re-sizing actually you want migrate either bigger or smaller hardware and keeping all the software installed on your existing machine should remain as it is.

b.    You must be running an EBS boot instance (not instance-store or S3-based AMI). Any files on ephemeral storage (e.g., /mnt) will be lost.

c.    You can only move to a different instance type of the same architecture (32-bit or 64-bit). 

d.    The private and initial public IP addresses of the instance will be different when it is running on the new hardware. Use an Elastic IP Address to keep the public IP address the same.

e.    There will be a short outage while the instance is moved to new hardware (roughly equivalent to the reboot time of normal hardware).

22. If the root device for your instance is an instance store volume and want to resize it, you must migrate your application to a new instance with the instance type that you want. 

23. When you resize an instance, the resized instance usually has the same number of instance store volumes that you specified when you launched the original instance. If you want to add instance store volumes, you must migrate your application to a completely new instance with the instance type and instance store volumes that you want. An exception to this rule is when you resize to a storage-intensive instance type that by default contains a higher number of volumes. 

24. You can't resize an instance that was launched from a PV AMI to an instance type that is HVM only. (Virtualization compatibility is required)

25. You must stop your Amazon EBS–backed instance before you can change its instance type.

26. When you stop and start an instance, be aware of the following:

·         We move the instance to new hardware; however, the instance ID does not change.

·         If your instance is running in a VPC and has a public IP address, we release the address and give it a new public IP address. The instance retains its private IP addresses and any Elastic IP addresses.

·         If your instance is in an Auto Scaling group, the Auto Scaling service marks the stopped instance as unhealthy, and may terminate it and launch a replacement instance. To prevent this, you can suspend the Auto Scaling processes for the group while you're resizing your instance.

27. To ensure that your users can continue to use the applications that you're hosting on your instance uninterrupted, you must take any Elastic IP address that you've associated with your original instance and associate it with the new instance. 

28. Resizing in-compatible instance (Changing the instance type): If the current configuration of your instance is incompatible with the new instance type that you want, then you can't resize the instance to that instance type. Instead, you have to migrate your application to a new instance with a configuration that is compatible with the new instance type that you want.

29. Amazon EC2 provides the following purchasing options to enable you to optimize your costs based on your needs:

·         On-Demand instances — pay, by the hour, for the instances that you launch.

·         Reserved Instances — Purchase, at a significant discount, instances that are always available, for a term from one to three years.

·         Scheduled Instances — Purchase instances that are always available on the specified recurring schedule, for a one-year term.

·         Spot instances — Bid on unused instances, which can run as long as they are available and your bid is above the Spot price, at a significant discount. (Like you buy shares in stock market, based on bid price)

·         Dedicated hosts — Pay for a physical host that is fully dedicated to running your instances, and bring your existing per-socket, per-core, or per-VM software licenses to reduce costs.

·         Dedicated instances — Pay, by the hour, for instances that run on single-tenant hardware.

30. If you require a capacity reservation, consider Reserved Instances or Scheduled Instances.

31. Spot instances are a cost-effective choice if you can be flexible about when your applications run and if they can be interrupted. 

32. Dedicated hosts can help you address compliance requirements and reduce costs by using your existing server-bound software licenses. If you have any existing software licenses which are bound to server e.g. Simulator Keys of , then you can use dedicated hosts, whose hardware does not changes.

33. Amazon EC2 launches the instances and then terminates them three minutes before the time period ends.

34. Reserved Instances provide you with a significant discount compared to On-Demand instance pricing. In addition, when Reserved Instances are assigned to a specific Availability Zone, they provide a capacity reservation. 

35. Each Reserved Instance that is specific to an Availability Zone can also provide a capacity reservation.

36. Generally speaking, you can save more money choosing Reserved Instances with a higher upfront payment. There are three payment options (No Upfront, Partial Upfront, and All Upfront) and two term lengths (one-year or three-years).

37. You can find Reserved Instances offered by third-party sellers at shorter term lengths and lower prices as well. 

38. When you purchase a Reserved Instance, the reservation is automatically applied to running instances that match your specified parameters.

39. Reserved Instances do not renew automatically; you can continue using the EC2 instance without interruption, but you will be charged On-Demand rates. 

40. You can use Auto Scaling or other AWS services to launch the On-Demand instances that use your Reserved Instance benefits. 

41. Both Standard and Convertible Reserved Instances can be purchased to apply to instances in a specific Availability Zone, or to instances in a region. Reserved Instances purchased for a specific Availability Zone can be modified to apply to a region—but doing so removes the associated capacity reservation.

42. Convertible Reserved Instances can be exchanged for other Convertible Reserved Instances with entirely different configurations, including instance type, platform, or tenancy. It is not possible to exchange Standard Reserved Instances in this way.

43. Convertible Reserved Instances— Only Amazon EC2 Standard Reserved Instances can be sold in the Reserved Instance Marketplace. Convertible Reserved Instances cannot be sold.

44. Other AWS Reserved Instances, such as Amazon RDS and Amazon ElastiCache Reserved Instances cannot be sold in the Reserved Instance Marketplace.

45. Convertible Reserved Instances are not available for purchase in the Reserved Instance Marketplace.

46. When your computing needs change, you can modify your Standard Reserved Instances and continue to benefit from your capacity reservation. Convertible Reserved Instances can be modified using the exchange process. 

47. Scheduled Instances are a good choice for workloads that do not run continuously, but do run on a regular schedule. For example, you can use Scheduled Instances for an application that runs during business hours or for batch processing that runs at the end of the week.

48. Scheduled Reserved Instances (Scheduled Instances) enable you to purchase capacity reservations that recur on a daily, weekly, or monthly basis, with a specified start time and duration, for a one-year term. 

49. If you are flexible about when your instances run, Spot instances might meet your needs and decrease costs.

50. Amazon EC2 sets aside pools of EC2 instances in each Availability Zone for use as Scheduled Instances. Each pool supports a specific combination of instance type, operating system, and network (EC2-Classic: this means shared network or EC2-VPC: This means private network for each account).

51. You can't stop or reboot Scheduled Instances, but you can terminate them manually as needed. 

52. If you terminate a Scheduled Instance before its current scheduled time period ends, you can launch it again after a few minutes. Otherwise, you must wait until the next scheduled time period.

53. Scheduled Instances are subject to the following limits:

·         The following are the only supported instance types: C3, C4, M4, and R3.

·         The required term is 365 days (one year).

·         The minimum required utilization is 1,200 hours per year.

·         You can purchase a Scheduled Instance up to three months in advance.

54. Spot instances enable you to bid on unused EC2 instances, which can lower your Amazon EC2 costs significantly. The hourly price for a Spot instance (of each instance type in each Availability Zone) is set by Amazon EC2, and fluctuates depending on the supply of and demand for Spot instances. Your Spot instance runs whenever your bid exceeds the current market price.

55. Spot instances are a cost-effective choice if you can be flexible about when your applications run and if your applications can be interrupted. For example, Spot instances are well-suited for data analysis, batch jobs, background processing, and optional tasks

56. Spot instance interruption—Amazon EC2 terminates your Spot instance when the Spot price exceeds your bid price or there are no longer any unused EC2 instances. Amazon EC2 marks the Spot instance for termination and provides a Spot instance termination notice, which gives the instance a two-minute warning before it terminates.

57. You can create launch configurations with a bid price so that Auto Scaling can launch Spot instances. 

58. There are scenarios where it can be useful to run Spot instances in an Amazon EMR cluster.

59. AWS CloudFormation (form your infrastructure in cloud: everything define in a template file and AWS create infrastructure for you) enables you to create and manage a collection of AWS resources using a template in JSON format. AWS CloudFormation templates can include a Spot price. 

60. When you use Spot instances, you must be prepared for interruptions. Amazon EC2 can interrupt your Spot instance when the Spot price rises above your bid price, when the demand for Spot instances rises, or when the supply of Spot instances decreases.

61. Note that you can't stop and start an Amazon EBS-backed instance if it is a Spot instance, but you can reboot or terminate it.

62. Note that you can't stop and start an Amazon EBS-backed instance if it is a Spot instance, but you can reboot or terminate it.

·         Shutting down a Spot instance on OS-level results in the Spot instance being terminated. It is not possible to change this behavior.

63. Specify an Availability Zone group in your Spot instance request to tell the Spot service to launch a set of Spot instances in the same Availability Zone. Note that Amazon EC2 need not terminate all instances in an Availability Zone group at the same time. If Amazon EC2 must terminate one of the instances in an Availability Zone group, the others remain running.

64. A Spot fleet is a collection, or fleet, of Spot instances. The Spot fleet attempts to launch the number of Spot instances that are required to meet the target capacity that you specified in the Spot fleet request. The Spot fleet also attempts to maintain its target capacity fleet if your Spot instances are interrupted due to a change in Spot prices or available capacity.

·         A Spot instance pool is a set of unused EC2 instances with the same instance type, operating system, Availability Zone, and network platform (EC2-Classic or EC2-VPC). 

65. The following instance types are not supported for Spot:

·         T2 , HS1

66. By default, there is an account limit of 20 Spot instances per region.

67. Spot instances EBS encryption is not supported: You can specify encrypted EBS volumes in the launch specification for your Spot instances, but these volumes are not encrypted.

68. An Amazon EC2 Dedicated Host is a physical server with EC2 instance capacity fully dedicated to your use. Dedicated Hosts allow you to use your existing per-socket, per-core, or per-VM software licenses

69. Dedicated Hosts and Dedicated Instances are different things: Dedicated Hosts and Dedicated Instances can both be used to launch Amazon EC2 instances onto physical servers that are dedicated for your use.

·         There are no performance, security, or physical differences between Dedicated Instances and instances on Dedicated Hosts. However, Dedicated Hosts give you additional visibility and control over how instances are placed on a physical server.

70. When you use Dedicated Hosts, you have control over instance placement on the host using the Host Affinity and Instance Auto-placement settings.

71. With Dedicated Instances, you don't have control over which host your instance launches and runs on (Underline hardware changes: e.g. Simulator Keys of , then you cannot use dedicated instances, whose hardware does changes). If your organization wants to use AWS, but has an existing software license with hardware compliance requirements, this allows visibility into the host's hardware so you can meet those requirements.

72. Dedicated Host Reservations provide a billing discount compared to running On-Demand Dedicated Hosts. Reservations are available in three payment options:

·         No Upfront—No Upfront Reservations provide you with a discount on your Dedicated Host usage over a term and do not require an upfront payment. Available for a one-year term only.

·         Partial Upfront—A portion of the reservation must be paid upfront and the remaining hours in the term are billed at a discounted rate. Available in one-year and three-year terms.

·         All Upfront (Highest cost saving)—Provides the lowest effective price. Available in one-year and three-year terms and covers the entire cost of the term upfront, with no additional charges going forward.

73. To use a Dedicated Host, you first allocate hosts for use in your account. You then launch instances onto the hosts by specifying host tenancy for the instance. The instance auto-placement setting allows you to control whether an instance can launch onto a particular host. When an instance is stopped and restarted, the Host affinity setting determines whether it's restarted on the same, or a different, host.