Azure storage services
📘Microsoft Certified: Azure Fundamentals (AZ-900)
Overview
Azure provides different storage tiers to store your data based on how often it is accessed and how long it needs to be stored. Using the right tier helps save costs while keeping data available when needed. Azure storage tiers apply mainly to Blob Storage, which is used for unstructured data like documents, images, videos, or backups.
The three main tiers are:
- Hot
- Cool
- Archive
1. Hot Tier
- Purpose: For data that is frequently accessed.
- Access Pattern: You expect to read and write this data often.
- Cost:
- Storage cost: Higher (because data is ready for instant access)
- Access cost: Low (cheap to read/write)
- Use Cases in IT:
- Active databases backups
- Frequently accessed files like daily logs
- Content used by apps regularly (like images or documents stored for a website)
Key Point: Hot tier is optimized for speed and frequent access, not for cost savings on storage.
2. Cool Tier
- Purpose: For data that is infrequently accessed, but still needs to be available quickly.
- Access Pattern: You rarely access this data, maybe monthly.
- Cost:
- Storage cost: Lower than Hot (cheaper to store)
- Access cost: Higher than Hot (reading/writing is more expensive)
- Use Cases in IT:
- Older backup files not accessed often
- Data that is used quarterly for reports
- Archived logs that might be needed occasionally for auditing
Key Point: Cool tier balances storage cost and access cost for data that is less frequently used but still needs to be available when requested.
3. Archive Tier
- Purpose: For data that is rarely accessed, and can tolerate hours of retrieval time.
- Access Pattern: You almost never need to access this data, but you want to keep it long-term.
- Cost:
- Storage cost: Very low (cheapest tier)
- Access cost: Very high (retrieving data may take hours)
- Access Time: Can take up to several hours to retrieve
- Use Cases in IT:
- Long-term compliance data or legal records
- Historical logs for audits
- Old backup files kept for years
Key Point: Archive tier is the cheapest for storage but not suitable if you need immediate access.
Quick Comparison Table
| Feature | Hot Tier | Cool Tier | Archive Tier |
|---|---|---|---|
| Access Frequency | Frequent | Infrequent | Rare |
| Storage Cost | High | Lower | Lowest |
| Access Cost (Read/Write) | Low | Higher | Highest |
| Retrieval Time | Instant | Instant | Hours |
| Example Use Case | Active files, logs | Quarterly backups | Long-term archives |
Exam Tips
- Remember the relationship between storage cost and access cost:
- Hot → pay more to store, but cheaper to access
- Archive → pay very little to store, but very expensive and slow to access
- Think in terms of access frequency:
- Hot → frequent
- Cool → occasional
- Archive → rare
- Use cases are often asked in scenario-based questions: The exam may describe a file or data type and ask which tier is most appropriate.
- Transitioning between tiers:
- Azure allows moving data between tiers if your access pattern changes.
- Example: A file might start in Hot, move to Cool after a month, and finally go to Archive after a year.
✅ Summary for Exam:
- Hot: Frequently accessed data, pay more to store, cheap to access
- Cool: Infrequently accessed data, cheaper to store, more expensive to access
- Archive: Rarely accessed data, very cheap to store, retrieval can take hours
