AWS EC2 Instances
EC2 Instances:
- On-demand instances
- Reserved instances
- Spot instances
- Dedicated hosts
- Scheduled instances
On-demand instances:
- These instances are charged per hour basis.
- When instances are not running, there are no charges.
- Even if instance is stopped, bill counts for EBS volumes attached to the instance.
- Use this instance type when we need instances for short duration (1 day, 1week, one month.
Reserved Instances:
- We can reserve instances either one or three years.
- The advantage of reserved instance is we can save up to 70% of the cost when compared with on-demand instances
- Once reserved purchase is done, there is no option to terminate the contract, only option is to sell it over AWS marketplace
- Reserved instance payment options: All upfront, Partial upfront and no upfront.
- AWS billing automatically applies discovered rates when you launch an instance that matches your purchase RI.
- EC2 Reserved instance has three types.
- 1. Standard
- 2. Convertible
- 3. Scheduled.
- RI’s can be shared across multiple accounts with in consolidated billing.
Spot Instances:
- Amazon EC2 spot instances allow you to bid on spare Amazon EC2 computing capacity for up to 90% off the on-demand price
- Spot instances are excess EC2 capacity that AWS tries to sell on an market exchange basis.
- Customer defines highest willing to pay for instance. If capacity is constrained and others are willing to pay more, your instance might get terminated or stopped.
- For “one time request”, instance is terminated and ephemeral data is lost.
- For “reqeust and maintain”, instance can be configured to terminate, hibernate or stop until price point can be met again.
Dedicated Hosts:
- A dedicated host is a physical EC2 server dedicated to your use.
- Dedicated hosts can help you reduce costs by allowing you to use your existing server-bound software license, including windows server, SQL server, SUSE linux etc.
Scheduled instances:
- We can buy instances based on your schedule.
- Example: if you need servers on daily, weekly, monthly basis and in dedicated hours for example: 4 to 5 hours per day, then you can go for scheduled instances.
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