AWSome Day Seattle Notes: Part 1: The Basics

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AWSome Day Notes: Part 1: The Basics

Following are some notes from Amazon's AWSome Day (Tuesday, February 27, 2018).

EC2 Costs and Scheduling

Cost of a node:

  • Important to understand Amazon's price model: users pay for access, not for hardware
  • Cost of AWS node is cost for on the spot access


  • If you can anticipate your usage, you can schedule instances in advance, and get a discount
  • Discount of 50% for one-year reservation (if you keep it busy for 6 months, you've made your money back)
  • Spot instances also available - need to be robust to sudden starts/stops (good for embarrassingly parallel jobs)
  • Cheaper to anticipate your usage and plan ahead

EC2 Transfer Costs

EC2 Instances:


  • Traffic going from the internet into a node is always free
  • Traffic going from the node out to the internet incurrs costs after 10 TB
  • Outbound traffic costs ~$90/TB

AWS Regions:

  • Traffic within a region does not incur costs (well... it's complicated)
  • Traffic between regions will incur costs


  • Transfer into an EC2 node from S3 bucket in same AWS region does not incur costs
  • Transfer out of an EC2 node into S3 bucket in same AWS region does not incur costs
  • (If they did charge you, they would be double-dipping...)

Note: the list of prices is like a legal document, so use the AWS Monthly Calculator to estimate monthly costs with more detail.

S3 Transfer Costs

  • See S3 Pricing - Data Transfer
  • Price model for storage is simliar to price model for AWS nodes: you pay for access, not for hardware
  • To give a sense of why, think about logistics of a large "disk farm": all the intensive operations are done by the head nodes, disks are just passive
  • Busier disk farm needs sophisticated hardware for parallel read/write, high-bandwidth network lines, fast encryption

S3 storage pricing:

  • Rule of thumb: ~$20/TB to store the data


  • Transfer into an S3 bucket from the internet is always free (getting stuff into the bucket is the easy part - that's how they get ya)
  • Transfer out of an S3 bucket to the internet costs ~$90/TB


  • Transfer out of an S3 bucket to most other Amazon regions costs ~$20/TB
  • Transfer out of an S3 bucket into an EC2 node in the same AWS region does not incur costs
  • Transfer into an S3 bucket from an EC2 node in the same AWS region does not incur costs

As mentioned above, this means you won't be double-charged for transferring data from an S3 bucket to an EC2 node, then from the EC2 node out to the internet.

S3 Storage Hierarchies

Continuing with the theme of planning ahead...

Storage hierarchies:

  • Biggest cost of storage is not disk space, it's transfer
  • Paying for speed, paying for timeliness, paying for on the spot access to your data
  • Your data will be cheaper if you're willing to wait a few minutes or deal with a slow connection

Storage hierarchies:

  • Standard (~$20/TB)
  • Infrequent access (~$13/TB) - less frequent access, but at same transfer speed
  • Glacier (~$4/TB) - delay of up to 12 hours (smaller files = faster), deleting data newer than 3 months incurrs costs

Glacier Pricing

Lifecycle rules: * Can create rules to move old data from S3 buckets into Glacier

EFS vs EBS vs S3

When do you use EFS, EBS, or S3?

Elastic Block Storage (EBS):

  • This is probably what you want
  • EBS is block storage for one EC2 node - designed for general purpose applications
  • Cost: ~$120/TB/mo

Elastic File System (EFS):

  • EFS is block storage for multiple EC2 nodes - designed for fast read-write operations, many incremental changes to files
  • "Elastic" part of EFS - can dynamically grow as hard drive grows (PB+ scale)
  • Hard drive on steroids - like plugging in a hard drive over a network, but big/fast/smart enough to be accessible to thousands+ of machines
  • Expensive: ~$300/TB/mo


  • S3 is object storage - it stores blobs of raw data, creates snapshots in time
  • If you change a single character of a large file, bucket has to create new shapshot
  • Booting from S3 as a hard disk would take you about a thousand years... don't do that
  • Cheapest: ~$20/TB

Cool but \($\):

  • You may see "appliances" mentioned in Amazon documentation - Amazon will ship you a physical data transfer appliance that encrypts and copies data on site (Snowball)
  • Can also purchase special network connections that bypass the public internet - like ISP putting alligator clips between your network lines and Amazon's network lines

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