What it is: Low-cost archival storage classes for S3.

What it’s for:

• Long-term retention where retrieval can take minutes to hours.

Key ideas:

• Glacier is used via S3 storage classes (Glacier / Deep Archive).
• Best paired with lifecycle rules.

Exam cues:

• “archive for years, cheapest, slow retrieval OK” → Glacier Deep Archive.

Hard words:

• *archive* /ˈɑːrkaɪv/: lưu trữ lâu dài
• *retention* /rɪˈtenʃn/: lưu giữ
• *retrieval time* /rɪˈtriːvəl taɪm/: thời gian lấy dữ liệu