Art of Codeartofcode
Lesson 8 of 16

11. Object / Blob Storage

1
The picture to keep in your head
2
11.1 What's the difference between block, file and object storage?
3
11.2 Why not just store files in the database?
4
11.3 What are buckets, keys and metadata?
5
11.4 How do uploads work with presigned URLs?
6
11.5 How do you upload very large files reliably?
7
11.6 How does object storage avoid losing files?
8
11.7 What are storage classes and lifecycle rules?
9
11.8 How should files be served to users?
10
11.9 What happens after a file is uploaded?
11
Memory card and where the analogy breaks
12
Practice: five levels
13
Interview questions
14
Solutions
15
Sources
16
Code lab
11. Object / Blob Storage

11.7 What are storage classes and lifecycle rules?

3 min read+10 XP

At the cloakroom: Coats collected tonight hang by the door. Lost-property items unclaimed for a month go to the back room. After a year, they go to the basement, cheap to keep but slow to fetch. After two years, they're given away.

In the system: Object stores offer storage classes with different prices for storing and reading:

Class (S3 names; others are similar)Good forTrade-off
StandardData read often (covers, current e-books)Highest storage price, cheapest to read
Infrequent AccessRead rarely but must be instant (old invoices)Cheaper to store, a fee per read, minimum storage time
Archive (Glacier tiers)Kept for years, almost never read (old logs, compliance records)Cheapest to store; reading can take minutes to hours, plus fees

Google Cloud Storage has Standard, Nearline, Coldline and Archive along the same lines.

Lifecycle rules move or delete objects automatically by age or prefix:

rule 1: logs/* → Infrequent Access after 30 days → Archive after 180 days → delete after 3 years rule 2: uploads/tmp/* → delete after 1 day rule 3: unfinished multipart uploads → delete after 7 days

This is how storage bills stay sane as data grows every day (Chapter 2, section 2.8). Check minimum storage durations and retrieval fees before archiving something you might need back quickly.

Memory code: "By the door, back room, basement, give away." Hot, cool, archive, delete.