A Simple Analogy

Azure Blob Storage is like a massive filing cabinet in the cloud. Store documents, images, videos, logs—any file. Organize them in containers, control access, and retrieve them globally at high speed.

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What Is Blob Storage?

Azure Blob Storage is managed object storage for unstructured data: files, videos, images, backups, logs. It scales massively and costs pennies per GB.

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Blob Tiers

| Tier | Access | Cost | Use Case | |------|--------|------|----------| | Hot | Frequent access | Higher | Active files | | Cool | Infrequent | Lower | Backup, archive | | Archive | Rare access | Lowest | Long-term archive |

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.NET Advanced Operations

using Azure.Storage.Blobs;
using Azure.Storage.Blobs.Models;

var client = new BlobContainerClient(
    new Uri("https://myaccount.blob.core.windows.net/container"),
    new DefaultAzureCredential());

// Upload with metadata
var blobClient = client.GetBlobClient("documents/report.pdf");
await blobClient.UploadAsync(stream, overwrite: true);

await blobClient.SetMetadataAsync(new Dictionary<string, string>
{
    { "Department", "Finance" },
    { "CreatedBy", "John Doe" }
});

// List blobs with filter
await foreach (var blobItem in client.GetBlobsAsync(
    BlobTraits.Metadata, 
    BlobStates.None, 
    "documents/"))
{
    var blob = client.GetBlobClient(blobItem.Name);
    Console.WriteLine($"{blob.Name}: {blobItem.Metadata["Department"]}");
}

// Soft delete and restore
var deletedBlobs = await client.GetBlobsAsync(BlobStates.Deleted);
foreach (var deletedBlob in deletedBlobs)
{
    await client.GetBlobClient(deletedBlob.Name).UndeleteAsync();
}

// Snapshot for backup
var snapshot = await blobClient.CreateSnapshotAsync();

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Practical Example: Log Archive

public class LogArchiveService
{
    private readonly BlobContainerClient _containerClient;
    
    public async Task ArchiveOldLogsAsync()
    {
        // List logs older than 30 days
        var cutoffDate = DateTime.UtcNow.AddDays(-30);
        
        await foreach (var blob in _containerClient.GetBlobsAsync(BlobTraits.Metadata))
        {
            if (blob.Properties.CreatedOn < cutoffDate)
            {
                // Move to archive tier
                await _containerClient.GetBlobClient(blob.Name)
                    .SetAccessTierAsync(AccessTier.Archive);
            }
        }
    }
    
    public async Task<Stream> DownloadLogAsync(string logName)
    {
        var blobClient = _containerClient.GetBlobClient(logName);
        var download = await blobClient.DownloadAsync();
        return download.Value.Content;
    }
}

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SAS URL Generation

// Generate temporary access URL
var sasUri = _containerClient.GenerateSasUri(
    Azure.Storage.Sas.BlobContainerSasPermissions.Read,
    DateTimeOffset.UtcNow.AddHours(1));

// Share URL without exposing account key
return sasUri.ToString();

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Best Practices

1. Use lifecycle policies: Auto-archive old data
2. Enable soft delete: Recover accidentally deleted data
3. Implement SAS tokens: Temporary, limited access
4. Monitor costs: Track storage by tier
5. Encrypt data: Use customer-managed keys

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Related Concepts

• Lifecycle management policies
• Replication strategies
• Shared Access Signatures (SAS)
• Backup and disaster recovery
• Data Lake Storage (hierarchy)

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Summary

Azure Blob Storage provides scalable, cost-effective storage with advanced features like tiering, snapshots, and soft delete. Use these features to optimize costs while maintaining data durability.