Blob Storage (Containers, Access Tiers, Lifecycle)
Blob Storage is Azure’s object storage solution for unstructured data — things like documents, videos, images, logs, and backups. It’s scalable, cost-effective, and central to many exam scenarios.
Blob Storage Structure
- Storage Account → Top-level container (like a warehouse).
- Blob Container → Sub-folder inside the storage account (like a section in the warehouse).
- Blobs → Actual files (objects) inside the container.
Blob Types
- Block Blob: For text and binary data (documents, media, backups).
- Append Blob: Optimized for append operations (log files).
- Page Blob: Used for virtual hard drives (VHDs), powering Azure disks.
Access Tiers
Azure lets you choose a cost vs performance tradeoff:
- Hot: Optimized for frequent access, higher storage cost, lower access cost.
- Cool: For infrequently accessed data, lower storage cost, higher access cost.
- Archive: For rarely accessed data, cheapest storage, but takes hours to rehydrate before use.
Lifecycle Management
- Rules can automatically move data between Hot, Cool, and Archive tiers.
- You can auto-delete old blobs after X days (great for logs or temporary data).
Blob Snapshots & Versions
- Snapshots: Read-only versions of a blob at a specific point in time.
- Blob Versioning: Automatically maintains previous versions when a blob is overwritten.
Confusion Buster 🚨
Blob Snapshots vs Disk Snapshots
– Blob snapshot = version of a file in object storage.
– Disk snapshot = point-in-time backup of an entire managed disk.
Exam trick: If the question says “snapshot of a blob,” it’s not the same as VM disk snapshot.
Simple Example
Your company stores monthly reports in Blob Storage. Hot tier for this month’s report (frequent access), Cool tier for last year’s reports, and Archive for anything older than 5 years. Lifecycle rules can automate this movement.
Exam Tip
If you see “rarely accessed” or “cheapest storage”, the answer is Archive. If you see “frequent read/write”, the answer is Hot or Block Blob. If logs are mentioned, think Append Blob.
What to Expect in the Exam
- Direct Q: “Which blob type is best for logs?” → Append Blob.
- Scenario: “Company wants to minimize cost for data accessed once a year.” → Archive tier.
- Trick Q: “Archive tier allows instant access.” (False — rehydration required).
- Scenario: “You want automatic tiering of data.” → Use Lifecycle Management rules.