S3: Consistency, Classes, Lifecycle

S3: Consistency, Classes, Lifecycle

Step 1 of 10

classStandard

A bucket is a flat namespace of keys. Every object also has a storage class; Standard is the default.

The Idea

S3 stores objects under keys in a bucket, and reads are strongly consistent: after a successful PUT or DELETE, the next GET or LIST sees it. Every object has a storage class — Standard for hot data, Standard-IA and Glacier Instant Retrieval for rare reads, and archive classes (Glacier Flexible Retrieval, Deep Archive) that must be restored before reading.

Real-World Example

A photo app's originals are opened constantly for a week and almost never after six months. One lifecycle rule moves them to Standard-IA at 30 days, to Glacier Flexible Retrieval at 180, and expires them at a year — no cleanup job to maintain.

The Tradeoff

Colder classes charge per-GB retrieval fees and bill minimum storage durations, so moving short-lived or tiny objects can cost more than leaving them. When access is unpredictable, S3 Intelligent-Tiering moves objects between tiers for you, with no retrieval fees.

Hands-On

# illustrative — needs an AWS account; bucket name is a placeholder
aws s3api put-bucket-lifecycle-configuration --bucket photos-bucket \
  --lifecycle-configuration file://lifecycle.json
# lifecycle.json
# {"Rules": [{"ID": "age-out", "Status": "Enabled", "Filter": {"Prefix": "raw/"},
#   "Transitions": [{"Days": 30, "StorageClass": "STANDARD_IA"},
#                   {"Days": 180, "StorageClass": "GLACIER"}],
#   "Expiration": {"Days": 365}}]}

Your turn

Put the steps in the right order.

1. 1The expiration action deletes the object↑↓
2. 2The object is uploaded to S3 Standard↑↓
3. 3It moves to Glacier Flexible Retrieval; a read now needs a restore↑↓
4. 4It moves to Standard-IA once reads become rare↑↓

Check order

Mini quiz

1 / 3

You overwrite an object and immediately GET it. What does S3 return?

• APossibly the old version for a few seconds
• BThe new version — reads after a successful write are strongly consistent
• CAn error until replication finishes
• DWhichever copy is closest to you

Sources

• What is Amazon S3? (consistency model) — Amazon S3 User Guide
• Understanding and managing S3 storage classes — Amazon S3 User Guide
• Managing the lifecycle of objects — Amazon S3 User Guide
• put-bucket-lifecycle-configuration — AWS CLI Reference