EC2 Flashcards
Q: What is a reservation ID? Do reservation IDs only apply to Reserved Instances?
Reservation IDs apply to all instances, and are different from Reserved Instances.
Every instance launched by EC2 has…
…a reservation ID
What is the relationship between a reservation ID and an instance launch request?
1:1, but a request can be associated with more than one instance if you launch multiple instances using the same launch request
How do you return the reservation ID?
DescribeInstances API
You can start your AMI on any number of On-Demand instances by using the…
…RunInstances API call
How many On-Demand instances are you limited to?
20
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
You can also programmatically terminate any number of your instances using the…
…TerminateInstances API
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
when you are ready to restart the associated instance with the Amazon EBS boot partition…
…use the StartInstances API
Q: What is the difference between using the local instance store and Amazon Elastic Block storage (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 is dependant 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.
An Amazon Machine Image (AMI) is simply
a packaged-up environment that includes all the necessary bits to set up and boot your instance
