Save some bucks on AWS with these pointers(Part 1)

Are you sure your ISV has kept these simple pointers in mind when deploying your multi-module app on AWS??

Instance Addressing

  • All Amazon EC2 instances are assigned two IP addresses at launch: a private address (RFC 1918) and a public address that are directly mapped to each other through Network Address Translation (NAT). Private addresses are only reachable from within the Amazon EC2 network. Public addresses are reachable from the Internet.
  • Amazon EC2 also provides an internal DNS name and a public DNS name which map to the private and public IP addresses respectively. The internal DNS name can only be resolved within Amazon EC2. The public DNS name resolves to the public IP address outside the Amazon EC2 network and the private IP address within the Amazon EC2 network
  • This private address is associated exclusively with the instance for its lifetime and is only returned to Amazon EC2 when the instance terminates.
  • Always use the internal address when you are communicating between Amazon EC2 instances. This ensures that your network traffic follows the highest bandwidth, lowest cost, and lowest latency path through our network.
  • Amazon EC2 instances that access other instances through their public NAT IP address are charged for Regional or Internet data transfer, depending on whether the instances are in the same Region.
  • To ensure customers are efficiently using elastic IP addresses, Amazon imposes a small hourly charge when these IP addresses are not mapped to an instance. When these IP addresses are mapped to an instance, they are free of charge.


    Watch this space for more pointers!!!

    Until Next time!!


  • Do you want to Stop or Terminate your EC2 instance?? What happens to your backup??

    So you are done for the day and stop your EC2 Instance.

    But are you sure you want to “stop” and not “terminate” it? What’s the difference?


    • You can stop an Amazon EBS-backed instance, but not an Amazon S3-backed instance.
    • Stopping causes the instance to stop running (its status goes from running to stopping to stopped). A stopped instance persists in Amazon EBS, which allows it to be re-started.
    • Stopping is different from terminating; you can’t re-start a terminated instance. Because Amazon S3-backed AMIs can’t be stopped, they’re either running or terminated. For more information about what happens and what you can do while an instance is stopped, see Stop/Start
    • When the instance is stopped, you’re not charged for any instance hours, only the volume storage. Each time you transition an instance from stopped to started, Amazon charges a full instance hour, even if transitions happen multiple times within a single hour
    • If you were using an elastic IP address with the instance, the address is automatically unmapped when the instance stops. While the instance is stopped, you’re charged for the address being unmapped (unless you remap it to another instance).
    • The root device volume and any others that you added either at the time of launch (through block device mapping) or after launch (by attaching volumes) remain attached while the instance is stopped. Any ephemeral storage does not persist. While the instance is stopped, you can’t change which devices are mapped to the instance.
    • Each Amazon EBS-backed instance has an attribute called InstanceInitiatedShutdownBehavior that controls whether the instance stops or terminates when you initiate a shutdown from within the instance itself. The default is stop. You can modify the attribute while the instance is running or stopped


    • When an instance terminates, any ephemeral storage is deleted.
    • By default, any volumes that were created when the instance launched (the root device and any others specified in the block device mapping) are automatically deleted when the instance terminates
    • However, any volumes that you attached after the instance was running are not deleted. If you detach and then re-attach a volume that was created at instance launch, it’s treated like a new volume that you attached after the launch, it will persist after instance termination and you will continue being charged for it unless you terminate it…

    So..keep a tight eye on the Instances and Volumes tab of the AWS Console to realize what is alive and accruing cost!!!


    Gearing up for AWS EC2:- Step 1. Decide your backup!


    Ready to deploy your application on the Amazon Cloud? You told your service integrator to provision a machine and put up your app. Did you discuss with him what kind of storage and back up your application would get?

    Most types of instances include a fixed amount of storage space on which you can store data. It is referred to as the “instance store” or an “ephemeral drive” as it is not designed to be a permanent storage solution.

    If an instance reboots (intentionally or unintentionally), the data on the instance store will survive. However, if the underlying drive fails, or if you stop or terminate the instance, the data is lost. Also, the data on the instance store is not included when you bundle an AMI. For example, if you have an Amazon S3-backed Windows instance, the D: drive on that instance is by default an ephemeral drive, which is not included in an AMI that you bundle from that instance.

    There are two options for your EC2 instance i.e to be backed by Amazon S3  or to be backed by Amazon EC2 and the option you select has an impact on the boot time,  data persistence and cost effectiveness of your deployment..

    Here is a brief from the Amazon EC2 official documentation.

    An Amazon EC2 instance can be launched from an AMI(Amazon Machine Instance) backed by Amazon EBS or from an AMI backed by Amazon S3. Instances launched from AMIs backed by Amazon EBS use Amazon EBS volumes as their root devices. Instances launched from AMIs backed by Amazon S3 use an instance store as the root device (e.g., / or C:\).

    The following table describes the differences between AMIs backed by Amazon EBS and AMIs backed by Amazon S3.


    If you are indeed thinking about going on the AWS, there are a lot of important decisions you will need to take..and we at Cennest can help you with the its for AWS!!

    Until next time!