CMSC389L

AWS Concepts

AWS Concepts

• Availability Zones (AZs) are individual isolated locations
  • Each AZ consists of multiple interconnected datacenters
• Regions are geographically-distributed groups of 2+ AZs
  • us-east-1 is Northern Virginia

Worksheet: AWS

Complete the first part of the worksheet, on AWS.

S3

S3

• Simple Storage Service (S3): Key-value store for object storage at scale
• Object Storage: Any sequence of bytes (photos, videos, source code, ...)
• Durability: 99.999999999%
  • Replicated across data centers and AZs
• Features: ACLs, Metadata, Versioning, Encryption, ...

When to use S3?

• S3: Think "file storage"
  • Support for large files, up to 5TB
  • Integration with CloudFront CDN
  • Support for archiving data (to Glacier)
  • examples: website static content (HTML/CSS/etc.), log files
• Databases: Think "queryable data"
  • DBMS guarantees
  • Faster read/writes
    • Index support
  • Limits on value size (f.e., 400Kb for DynamoDB)
  • examples: user profile data, credentials

S3: Case Study

• Mapbox: 
  • Used by Airbnb, Strava, Washington Post, etc.
• 100M miles of telemetry data / day
• 250M users, 11 countries, 10 regions
• Petabytes of map and imagery data
  • Rendered at 60FPS
  • Globally distributed with CloudFront

S3 Concepts

• Object: Fundamental entity in S3
  • Consists of object data + metadata
  • Metadata: name-value pairs that describe the object
    • date last modified, content-type, etc.
• Bucket: Container for objects stored in S3
  • Bucket name must be globally unique
  • Can store unlimited objects
• Key: Unique identifier within a bucket
  • 1-1 relationship between buckets and keys

Example: https://s3.amazonaws.com/cmsc389l/apple.png

S3 Operations

​Common Operations:

• Create Bucket: Creates a bucket in a specified region
• Write Object: Stores data at a given key, either by creating or overwriting
• Read Object: Returns an object, given a key
• Delete Object: Deletes an object, given a key
• List Keys: Lists all keys under a given prefix

S3 Guarantees

• Atomic: Reads to a previously updated object will return either the updated object or the previous object. Never partial or corrupted data.
  • Eventual Consistency: Update and delete operations are not available until fully replicated.
    • For new keys, reads have read-after-write consistency
• No Locks: Clients are responsible for implementing locks to prevent simultaneous updates

S3 Storage Types

• Frequently Accessed
  • Standard (default)
    • 99.999999999% durability, 99.99% availability
    • Most expensive storage class
  • Reduced Redundancy Storage (S3-RRS)
    • Reduced durability (​99.99%)
• Infrequently Accessed
  • Infrequently Accessed (S3-IA)
    • Reduced availability (99.9%) + retrieval fee
  • Glacier
    • No real-time access, access is on the scale of minutes to hours

S3 Features

• Versioning: If enabled, S3 stores all versions of a file
• Bucket Policies: Use policies to specify which services can access a bucket or key prefix
• Cross-Region Replication: Easily enable automatic data replication to other regions
• Lifecycle Management: Configurable rules based on object age. Supports transitioning and expiration
• Built-in Monitoring: via CloudWatch (GetRequests, BucketSizeBytes, 4xxErrors, FirstByteLatency, etc.)

S3 Costs

• Storage
  • Standard: $0.023 / GB-month
  • IA: $0.0125 / GB-month
  • Glacier: $0.004 / GB-month
• Data Transfer
  • Into S3: Free
  • Out of S3 to:
    • us-east-1: $0.010 / GB-month
    • Internet: $0.090 / GB-month
• Request Fee:
  • ​Writes: $0.05 / 10k requests
  • Reads: $0.004 / 10k requests

Worksheet: S3

Complete the second part of the worksheet, on S3.

CloudFront

CloudFront Concepts

• Content Delivery Networks (CDN): a globally-distributed network of proxy servers which cache content
  • Use cases: web streaming, static content acceleration

CDN Metrics

• Latency: Time taken until the first byte is downloaded
• Data Transfer Rates: Rate at which data is transferred to the client
• Cache Hit Ratio: The percent of requests where the data can be retrieved from the cache

CloudFront Concepts

• Edge Locations: Proxy server in the CloudFront network
• Regional Edge Caches: Proxy servers that intermediates between origin server and edge locations.

CloudFront Concepts

• Origin Server: The definitive store of content that CloudFront will accelerate (f.e., S3 or EC2 web server)
• Distribution: Configuration specifying your origin server, cache invalidation rules, etc. 

CloudFront Costs

• Transfer from CloudFront to Internet: $0.085 / GB
  • ​Varies by region and throughput
    • Drops to $0.020 / GB
• Transfer from AWS (S3, etc.) to CloudFront: Free
• Per-request fee: $0.01 / 10k requests

Worksheet: CloudFront

Complete the final part of the worksheet, on CloudFront.