====== S3 Storage Classes ======

**What it is:** Different cost/performance tiers for storing S3 objects.

**What it’s for:**
  * Optimize cost based on access frequency and retrieval needs.

**Common storage classes (exam-relevant):**
  * **S3 Standard**: frequent access.
  * **S3 Intelligent-Tiering**: automatically moves objects between tiers.
  * **S3 Standard-IA**: infrequent access (lower storage cost, retrieval fee).
  * **S3 One Zone-IA**: infrequent access, stored in one AZ (lower durability vs multi-AZ).
  * **S3 Glacier / Glacier Deep Archive**: archival storage.

**Exam cues:**
  * “unknown access pattern” → Intelligent-Tiering.
  * “infrequent access but must be available quickly” → Standard-IA.
  * “long-term archive, lowest cost, can wait hours” → Glacier Deep Archive.

**Hard words:**
  * *tier* /tɪr/: tầng/lớp
  * *infrequent* /ɪnˈfriːkwənt/: không thường xuyên
  * *retrieval* /rɪˈtriːvəl/: lấy dữ liệu ra
  * *archival* /ɑːrˈkaɪvəl/: lưu trữ lâu dài (archive)