☁️ Azure Storage Short Notes

🟢 What is Azure Storage?

• A cloud-based storage service for storing different types of data:
  • Unstructured (images, videos, docs).
  • Semi-structured (JSON, logs).
  • Structured (tables).
• Highly available, durable (replicated), and scalable.

👉 Think of it as different storage buckets under one umbrella.

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🟢 Core Azure Storage Services

1. Blob Storage → store unstructured data (images, docs, backups, logs).

   • Access tiers: Hot, Cool, Archive (cost vs. access trade-off).
   • Supports large file uploads (up to TBs).
   • Use cases: CDN, backups, static website hosting.

2. Table Storage → NoSQL key-value store.

   • Schemaless → good for semi-structured data.
   • Use cases: metadata, logs, user profile storage.

3. Queue Storage → message queuing for async communication.

   • Simple producer-consumer pattern.
   • Use cases: background jobs, task scheduling.
   • Max message size: 64 KB.

4. File Storage (Azure Files) → fully managed SMB file shares in the cloud.

   • Mountable by Windows, Linux, macOS.
   • Use cases: legacy app migration, shared file systems.

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🟢 Redundancy Options (Replication)

• LRS (Locally Redundant Storage) → 3 copies within 1 datacenter.
• ZRS (Zone Redundant Storage) → across 3 availability zones.
• GRS (Geo-Redundant Storage) → across 2 regions, read-access optional (RA-GRS).

👉 Interview Tip: If asked “How does Azure ensure durability?” → Answer: by replication (LRS/ZRS/GRS).

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🟢 Security

• Shared Access Signatures (SAS) → grant temporary, limited access to storage.
• Managed Identity + RBAC → modern, secure access.
• Encryption → data is encrypted at rest and in transit (TLS).
• Private Endpoints → restrict access to VNET.

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🟢 Example: Upload to Blob in .NET

using Azure.Storage.Blobs;
using System;
using System.IO;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        string connStr = "<StorageAccountConnectionString>";
        string containerName = "mycontainer";

        // Create a client
        BlobContainerClient container = new BlobContainerClient(connStr, containerName);
        await container.CreateIfNotExistsAsync();

        // Upload file
        BlobClient blob = container.GetBlobClient("sample.txt");
        using FileStream fileStream = File.OpenRead("sample.txt");
        await blob.UploadAsync(fileStream, overwrite: true);

        Console.WriteLine("✅ File uploaded!");
    }
}

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🟢 Monitoring

• Azure Monitor + Storage Metrics → track capacity, transactions, latency.
• Diagnostic logs → audit operations on blobs/queues/files.

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🟢 Common Interview Questions

1. What are the different types of Azure Storage?
2. Difference between Blob Storage access tiers (Hot, Cool, Archive)?
3. When to use Queue Storage vs. Service Bus?
4. How do you secure access to Blob Storage?
5. What is SAS? How is it different from Managed Identity?
6. How does Azure ensure durability of storage?
7. Difference between Table Storage and Cosmos DB?
8. How do you host a static website in Blob Storage?

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🟢 Pros & Cons

✅ Pros

• Highly scalable & durable.
• Multiple redundancy & tiering options.
• Easy integration with Azure services.

❌ Cons

• Latency if accessed across regions.
• Costs can grow with frequent access.
• Queue Storage is basic (no topics, sessions → use Service Bus instead).

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✅ Quick Recap

• Blob → unstructured data (Hot/Cool/Archive).
• Table → NoSQL key-value store.
• Queue → simple messaging.
• Files → SMB shares.
• Secure with SAS + Managed Identity + RBAC.
• Replication options → LRS, ZRS, GRS.