Azure Blob Storage

Azure Blob Storage is Microsoft's object storage solution for the cloud. It is designed to store massive amounts of unstructured data — text, images, videos, logs, backups, and any binary data. This lesson covers the core concepts of Blob Storage, blob types, containers, access patterns, and common use cases.

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What Is Blob Storage?

Blob stands for Binary Large Object. Azure Blob Storage is optimised for storing enormous volumes of unstructured data that does not conform to a particular data model or definition.

Common Use Cases

• Serving images or documents directly to a browser
• Storing files for distributed access
• Streaming video and audio
• Storing data for backup and disaster recovery
• Storing data for analysis by on-premises or Azure-hosted services
• Hosting static websites

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Blob Storage Hierarchy

Blob Storage uses a three-level hierarchy:

Storage Account
  |
  |-- Container 1
  |     |-- Blob A
  |     |-- Blob B
  |     |-- virtual-folder/Blob C
  |
  |-- Container 2
        |-- Blob D

Level	Description
Storage Account	The top-level namespace. Provides a unique DNS endpoint.
Container	A logical grouping of blobs, similar to a directory. A storage account can contain unlimited containers.
Blob	The individual file or object. A container can contain unlimited blobs.

Container Naming Rules

• 3 to 63 characters
• Lowercase letters, numbers, and hyphens only
• Must start with a letter or number

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Blob Types

Azure Blob Storage supports three blob types, each optimised for different scenarios:

Block Blobs

Block blobs are made up of blocks of data that can be managed individually. They are the default and most commonly used blob type.

Feature	Detail
Max size	~190.7 TiB (up to 50,000 blocks of 4,000 MiB each)
Best for	Text, binary files, documents, media, general-purpose storage
Upload	Can upload blocks in parallel for faster transfers

Append Blobs

Append blobs are optimised for append operations. You can only add blocks to the end — you cannot modify or delete existing blocks.

Feature	Detail
Max size	~195 GiB
Best for	Logging, audit trails, telemetry data
Key property	Append-only — ideal for scenarios where data is written sequentially

Page Blobs

Page blobs are optimised for random read/write operations. They store data in 512-byte pages.

Feature	Detail
Max size	8 TiB
Best for	Virtual hard disks (VHDs) for Azure VMs (unmanaged disks)
Key property	Random access at the page level

Note: Azure Managed Disks (covered in a later lesson) are built on page blobs but abstract away the storage account management.

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Working with Blobs

Uploading Blobs (Azure CLI)

# Upload a single file
az storage blob upload \
  --account-name mystorageaccount \
  --container-name mycontainer \
  --name documents/report.pdf \
  --file ./report.pdf \
  --auth-mode login

# Upload a directory of files
az storage blob upload-batch \
  --account-name mystorageaccount \
  --destination mycontainer \
  --source ./local-folder \
  --auth-mode login

Downloading Blobs