AZ-900 Exam Cram: Azure Storage Services

This cram sheet focuses on Skill 2.3: Describe Azure Storage services for the Microsoft Azure Fundamentals exam. It covers storage types, redundancy, access tiers, and migration tools.

Topic Weighting

[!IMPORTANT] Storage is a high-yield topic because it is foundational to almost every other Azure service (Compute, Databases, AI).

Key Concepts Summary

Core Storage Services

• Azure Blobs: Highly scalable object store for unstructured data (images, logs, videos). Think "files in the cloud."
• Azure Files: Managed file shares for cloud or on-premises deployments (SMB/NFS). Ideal for "Lift and Shift" of file servers.
• Azure Disks: Block-level storage volumes for Azure VMs. Provides persistent storage for the OS and data.
• Azure Queues: Messaging store for reliable throughput between application components.
• Azure Tables: NoSQL store for schemaless storage of structured data (key-attribute pairs).

Access Tiers (Blob Storage)

• Hot Tier: Optimized for frequent access. Highest storage cost, lowest access cost.
• Cool Tier: Optimized for data stored for at least 30 days. Lower storage cost than Hot, higher access cost.
• Archive Tier: Optimized for data stored for at least 180 days. Lowest storage cost, but data is offline and requires "rehydration" (hours) to access.

Data Migration Tools

• AzCopy: Command-line utility for high-performance copying of data to/from Azure Storage.
• Azure Storage Explorer: GUI application for managing cloud storage resources on Windows, macOS, and Linux.
• Azure File Sync: Synchronizes on-premises Windows Servers with Azure Files for local caching.
• Azure Data Box: Physical appliance used to move massive amounts of data (terabytes/petabytes) when bandwidth is limited.

Visual Anchors

Choosing a Storage Service

Redundancy Visualization

\begin{tikzpicture}[node distance=2cm] \draw[thick, fill=blue!10] (0,0) rectangle (2,1.5) node[midway] {DC 1}; \draw[thick, fill=blue!10] (3,0) rectangle (5,1.5) node[midway] {DC 2}; \draw[thick, fill=blue!10] (6,0) rectangle (8,1.5) node[midway] {DC 3}; \draw[dashed] (-0.5,-0.5) rectangle (8.5,2.5); \node at (4,2.8) {\textbf{Availability Zone (ZRS Copy Distribution)}}; \draw[<->, thick] (2,0.75) -- (3,0.75); \draw[<->, thick] (5,0.75) -- (6,0.75); \end{tikzpicture}

Common Pitfalls

• Archive Tier Access: Don't assume you can read data from the Archive tier instantly. It must be moved to Hot or Cool first (rehydrated).
• LRS vs. GRS: Don't use LRS (Locally Redundant Storage) for mission-critical data. If the datacenter fails, the data is lost. Use GRS for regional disaster recovery.
• Public Access: Don't assume storage accounts are public by default. Azure now emphasizes secure-by-default configurations.
• Managed vs. Unmanaged Disks: Always prefer Managed Disks for VMs as Azure handles the storage account scaling and placement for you.

Mnemonics / Memory Triggers

• BFD (Big Friendly Data): Blob, File, Disk (The three most common storage types).
• "Hot is Fast, Archive is Last": Reminds you that Hot tier is for frequent use and Archive has the longest latency.
• Redundancy Levels: "Lazy Zebras Get Grass"
  • LRS: Local (1 Datacenter)
  • ZRS: Zone (3 Zones in 1 Region)
  • GRS: Geo (2 Regions)
  • GZRS: Geo-Zone (3 Zones + 2 Regions)

Formula / Equation Sheet

Practice Set

1. Scenario: A company needs to move 50 TB of data to Azure but has very limited internet bandwidth. Which service should they use?
   • Answer: Azure Data Box (Physical migration).
2. Scenario: Which storage service is best suited for migrating a legacy on-premises file share that uses the SMB protocol?
   • Answer: Azure Files.
3. True/False: Data in the Archive tier can be read immediately as long as you pay a higher access fee.
   • Answer: False (It requires rehydration which takes hours).
4. Scenario: You need to ensure your data is protected even if an entire Azure Region experiences a disaster. Which redundancy option is required?
   • Answer: GRS or GZRS.
5. Question: Which tool provides a graphical user interface to manage blobs and queues across multiple subscriptions?
   • Answer: Azure Storage Explorer.