What Is Azure Blob? How Blob Storage Works and What It Is Used For

The volume of data stored in the cloud is experiencing exponential growth. According to Cybersecurity Ventures, the amount of data stored in the cloud will reach 100 zettabytes by 2025. In other words, the cloud will store 50% of the world’s total data by 2025.

Cloud storage has changed the way businesses manage, store and access data. Cloud storage solutions offer flexibility, scalability and seamless data accessibility, making them a popular choice over traditional on-premises storage solutions. According to a recent study by Statista, in 2023, 75% of respondents revealed that 40% of their organization’s data stored in the cloud was sensitive.

When it comes to cloud storage, Azure Blob Storage emerges as a vital component, offering an efficient solution for storing and managing vast amounts of unstructured data. In this article, we will delve deep into Azure Blob, exploring how it works, the different types of blobs, storage tiers and security.

What is Azure Blob Storage?

Microsoft Azure Blob Storage is a cloud-based storage service within the Microsoft Azure platform. It is specifically designed for storing and managing massive amounts of unstructured data, such as documents, images, videos, documents, logs, backups and more.

Unstructured data refers to information that doesn’t adhere to a predefined data model or lacks a specific organizational structure. Unlike structured data, which fits neatly into databases and is organized in rows and columns, unstructured data doesn’t have a fixed format and often contains diverse types of information.

How Azure Blob Storage works

Azure Blob Storage operates on a robust architecture built around three fundamental components:

Storage accounts

A storage account is the primary container within Azure Blob Storage. It acts as a logical container for blobs and provides a unique namespace for the objects stored in it. These accounts come in different types, including General-purpose v2, block blob and page blob storage. Each type has its own performance and pricing characteristics, allowing businesses to choose the one that aligns with their specific needs.


You can create multiple containers within a storage account. These containers act as directories in file systems, helping to organize the stored data for easy accessibility. A single storage account can have multiple containers, with each container capable of storing an infinite number of blobs.


Blobs, short for Binary Large Objects, are the actual data objects stored within Azure Blob Storage. They can be thought of as files, such as texts, images, audio and videos. Each blob has a unique URL, also known as URI (Uniform Resource Identifier), which has the name of the account, container and blob for access. 

Figure 1: Components of Azure Blob Storage

Azure blob types

There are three types of Azure Blobs, each suited for different use cases:

Block blobs

Block blobs are designed to stream and store documents, images, videos and backups efficiently. They are made up of blocks of data and are ideal for large files. Block blobs support efficient uploads and downloads, making them suitable for scenarios where data seldom changes. Block blobs have a data capacity of up to 190.7 tebibyte (TiB). For better understanding, 1TiB equals roughly 1.1TB.

Append blobs

Like block blobs, append blobs are also made up of blocks. Append blobs are designed for scenarios where data is appended to an existing blob, such as when you are logging data. They are optimized for high write speeds and ensure that data is written in an ordered manner.

Page blobs

Page blobs are primarily used for VHD (Virtual Hard Disk) files associated with Azure Virtual Machines. They provide the ability to read and write data in smaller chunks, making them suitable for scenarios where random read/write operations are essential. 

Azure Blob Storage tiers

Azure Blob Storage provides different storage tiers optimized for various access patterns and cost-efficiency, such as hot, cool and archive tiers, allowing users to manage data based on its usage and access frequency.

Hot access

The hot access storage tier is optimized for frequently accessed data. It provides low-latency access and is suitable for data that requires frequent reads and writes.

Cool access

The cool access storage tier is designed for data with less frequent access. It offers a more economical choice for data that is accessed less often but must be readily available.

Archive access

Archive access is the most cost-efficient tier and is intended for data that is rarely accessed. Data in this tier is offline and requires retrieval before it can be accessed. It is a suitable choice for long-term archival and compliance needs. 

Azure Blob Storage security

Azure Blob Storage ensures robust security measures to safeguard stored data, providing a secure environment for users to manage their information effectively. Several security protocols and features provide comprehensive data protection within Azure Blob Storage:

  • Encryption: Azure Blob Storage encrypts data at rest by default using Microsoft-managed keys. It also allows customers to manage their encryption keys using Azure Key Vault. Additionally, data in transit is encrypted using secure transport protocols like HTTPS, ensuring confidentiality during transmission.
  • Access controls and permissions: Azure Blob Storage integrates with Azure Active Directory (Azure AD) for robust authentication and authorization mechanisms. Users can define granular access permissions using Shared Access Signatures (SAS) or Azure role-based access control (RBAC), allowing them to control who can access their data and the actions they can execute.
  • Compliance: Azure Blob Storage’s compliance certifications and adherence to industry standards reinforce trust and regulatory compliance for end users. It complies with various regulatory frameworks, including GDPR, HIPAA, ISO and SOC, meeting stringent security and compliance requirements. 

What is Azure Blob Storage used for?

Azure Blob Storage is a reliable solution catering to diverse data storage needs across industries. Its versatile functionalities make it a crucial tool for various purposes, ensuring scalability, security and accessibility for businesses of all sizes. Here are a few of the most common use cases:

  • Big data storage for analysis: Azure Blob Storage accommodates vast amounts of unstructured data, providing an optimal environment for storing data sets used in big data analytics. It allows businesses to manage and analyze large-scale data efficiently, enabling informed decision-making and valuable insights.
  • Video and audio storage for streaming: Azure Blob Storage facilitates seamless streaming capabilities by storing various multimedia files like videos and audio. It enables businesses to serve content to users across various platforms, ensuring a smooth and uninterrupted streaming experience.
  • Direct-to-browser serving of images and documents: Businesses leverage Azure Blob Storage to serve images and documents directly to end-users’ browsers. This capability ensures fast and efficient delivery of content, enhancing user experiences without overloading servers.
  • File storage for distributed access: It provides distributed access to files stored within containers, enabling multiple users or applications to access and modify data concurrently. Azure storage supports optimistic concurrency, pessimistic concurrency and last writer wins strategies to ensure multiple users can view and update data simultaneously. This distributed access facilitates collaboration and supports distributed applications seamlessly.
  • Data storage for backup and restore, disaster recovery and archiving: Azure Blob Storage serves as a reliable solution for data backup, restoration, disaster recovery and archiving purposes. You can configure operational backups, vaulted backups or both on your storage accounts to protect data stored in Azure Blob. 

Archive to Azure Blob with Unitrends

Backup copies offer an additional level of security for your data. It’s crucial to have data copies stored off-site to recover from unforeseen incidents, such as ransomware attacks or natural disasters. Additionally, it can be essential for clients needing specific data retention levels.

A significant aspect of our newly launched Gen 10 Backup appliances is our ability to write to Azure Blob, providing you with more choices to archive. You can now leverage your Azure Blob Storage to store Unitrends backup copies for off-site, long-term retention. This capability eliminates the need for a virtual appliance to store backups in Azure, drastically improving ease of use and lowering cloud costs. To store copies of your backups in your Azure environment, simply add the Azure Blob Storage container to your Unitrends appliance as a backup copy target, then add a job to copy backups to this container.

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