What is Blob Storage? Definition, Types, & How It Works

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Microsoft Azure Blob Storage makes stored data available to businesses over the internet. While data can be of any type, blob storage is particularly useful for storing media, such as audio and video, and frequently changing data, such as log files. A blob, or binary large object, is data in binary form.

This focus on unstructured data storage makes sense given the recent enterprise shift to managing and analyzing unstructured information. The age of carefully filed data and organized databases has given way to a blend of both structured and unstructured data: if enterprises use both, enterprises need to store and analyze both. To learn all about Azure Blob Storage and how it can help your organization, see below.

How blob storage works

Azure Blob Storage is an object storage solution that can store unstructured data, which includes email, video, and binary data. Blob Storage supports data streaming and random access use cases.

Users can access blob objects with HTTP/HTTPS protocols; blob storage is available through the internet. Storage accounts and the containers and blobs held inside them all have Universal Resource Identifiers (URIs), making them easily accessible in a web browser.

Applications that benefit from blob storage include:

  • Online media sharing, such as accessing images or videos directly through a browser
  • Media streaming, whether audio or video
  • Distributed file access
  • Log file storage and update
  • Disaster recovery (DR), including backup, archival and restoration
  • Massive dataset storage, including data used for analytical applications
  • Internet of Things (IoT) applications

Blob storage structure

Azure Blob Storage is hierarchical: a storage account holds unlimited containers, which organize individual blobs.

Storage account

The storage account has its own unique URI, which includes the account name that a user selects. Each stored object’s address will also have this account name. Azure blob storage accounts have three different tiers:

  1. General purpose v2: a standard account for blobs, file shares, queues, and tables
  2. Block blob: a premium account for block blobs and append blobs
  3. Page blob: a premium account designed only for page blobs

Choosing a suitable account type depends on the blobs your organization plans to use and the latency your storage use case requires.


Containers are the basic storage unit for a Microsoft Azure storage account. They’re unlimited within a single storage account. They organize blobs, making them easier for users to locate. Microsoft Azure compares containers’ function to a file system directory; this is useful for object storage in particular, since it stores unstructured data. A container also has a unique URI. Containers can store any number of blobs.


A blob consists of binary data stored as a single item. Blobs also have URIs. Users can name individual blobs, using between one and 1,024 characters to create the name. Blobs have different access permission levels that users can set to restrict viewing abilities for blobs and containers.

3 types of blobs

Azure Blob Storage users have three different blob types available to them.

Block blobs

Block blobs are subdivided into blocks and primarily intended for storage of media files, documents, text files, and binary files. Blocks can be of varying sizes, with a maximum size of 4000 MiB per block, in the most current Azure version. There may be anywhere up to 50,000 blocks per blob, giving a maximum block blob size of around 190.7 TiB.

Individual blocks within a block blob can be modified or replaced, and blocks can be added to or deleted from the block blob. Parallel uploading of individual blocks optimizes the upload time for block blobs as well.

Append blobs

Append blobs also consist of blocks and are specifically designed for use with append operations. The most common use of an append blob is for storage and updating of log files. Blocks may be appended to the end of an append blob, but previously existing blocks may not be modified or deleted.

Just as with block blobs, an append blob may contain up to 50,000 blocks, each up to 4 MiB.

Page blobs

A page blob is intended for read and write operations. A page blob is an assembly of 512-byte pages, with a maximum page blob size of 8 TiB. Page blobs are useful for storage of items such as operating systems and disaster recovery data.

Also take note that all blobs, regardless of type, come encrypted due to the fact that they are cloud-based. Cloud encryption in general will encode data when it travels between cloud-based storage or applications and to users at their respective locations.

Advantages of blob storage

Azure Blob Storage has multiple benefits:

  • It supports unstructured data. Enterprise demands for storing and analyzing large volumes of unstructured data have increased over the past decade, and Azure Blob Storage is one solution that meets that need.
  • It supports multiple programming languages. Dev teams can use Go, Java, .NET, Node.js, PHP, Python, or Ruby to access their organization’s blob storage.
  • It’s available over the internet. It’s readily accessible for storage teams if they only have a computer and Wi-Fi.
  • It still has organizational features. Despite being designed for unstructured data,  containers allow businesses to create their preferred categories by uploading certain blobs to specific containers.

Disadvantages of blob storage

Azure has disadvantages for some users, too:

  • Transferring large volumes of data from Azure into a different tier or another platform can be expensive
  • South America has one cloud region, and Africa and Canada have two, so users in those regions that aren’t close to those locations may experience slower data speeds

Top 3 use cases of blob storage

Blob storage is a useful storage technology for multiple business technology operations, including big data analytics, backups, and data ingestion.

Big data

Blob storage can help enterprises manage large volumes of data, particularly if they want to perform big data analysis on that data. Because blob storage supports unstructured data, it can store multiple formats of enterprise information. That data is then available for large-scale analytics.

Microsoft’s big data analytics platform, Azure Data Lake Storage Gen2, is built on Azure Blob Storage. Microsoft customers who want to invest in a data analytics solution may benefit from using Gen2 alongside their blob storage account.


Businesses can keep backed-up data copies in an Azure Blob Storage storage account, ready to be restored to an enterprise system if it goes down. You’ll want to choose an account type designed for low latencies for applications that are high-performance or require immediate restoration. Users can also restore SQL Server data to Azure Blob Storage.

Data ingestion

Data can be ingested from Azure Blob Storage to platforms like SQL Azure databases, HDInsight, and Azure Machine Learning. Teams that want to pull stored data into applications , like ML and Hadoop, will benefit from Azure Blob Storage’s ingestion capabilities.

3 Azure Blob Storage pricing tiers

There are two types of costs associated with blob storage: transaction costs, or costs for accessing the data, and storage costs. Transaction costs are per block, and a write operation on one block is a single transaction.

Blob storage pricing is divided into three tiers, based on frequency of access to the data. This allows for more cost-efficient storage, particularly where the user has large amounts of data that require very infrequent access.


Hot storage is for the most frequently accessed data. It has the highest storage cost of the three tiers. Hot blob storage is always online, and it’s suitable for data that supports high-performance enterprise applications.


Cool storage is for data that is periodically accessed but not with great frequency. Cool blob storage is appropriate when data is not accessed more than once every 30 days. Cool storage has a lower storage cost than hot storage but higher transaction costs. Like hot storage, cool data is always online.

Learn more about storing cold data.


Archival storage is for data that requires long-term storage and very infrequent access — less than once every 180 days. It has the lowest storage cost and the highest transactional cost. Archival data storage is always offline. Users can optimize their archive costs by using data life cycle policies.

Learn more about the data archiving market.

Top alternatives to Azure Blob Storage

If you’re not sure that Azure is right for your business, these other enterprise storage solutions provide similar features to Azure Blob Storage.

IBM Cloud Object Storage

IBM’s cloud solution for unstructured data storage provides automatic tiering dependent on storage use; this is beneficial for storage teams with rapidly changing data access patterns. Administrators can set role-based access controls and permissions to protect their enterprise data. IBM also has an option for rapidly restoring archive data, with a restore time of up to 2  hours.

Google Cloud Storage

Google Cloud Storage is a managed service for unstructured volumes of data. Its automated storage tiering shifts objects between storage classes based on their access timeline. Google Cloud Storage can connect to other tools, like BigQuery and Vertex AI, for big data analytics, data warehousing, and machine learning modeling. Its security features include data encryption, retention policies, and access control policies.

Amazon Simple Storage Service (S3)

Amazon S3 for object storage is an internet-based solution, like Blob Storage. S3’s replication features help businesses meet their recovery time objectives (RTOs) and recovery point objectives (RPOs) for disaster recovery. Amazon’s archive storage classes, the Glacier tiers, are cost-effective options for long-term archive data. For big data and analytics purposes, enterprises can build a data lake on top of S3.

Bottom line: Azure Blob Storage for your enterprise’s unstructured data

Azure Blob Storage meets a core need for many enterprises: easy-to-access object storage for unstructured data. Its unlimited blob and container options make it good for large volumes. Enterprises produce massive amounts of data, and it’s critical for them to store information that comes in various formats and import it for analysis whenever needed.

Azure Blob Storage is suitable both for data that needs to be quickly accessed and rarely accessed archive data. It supports multiple storage account and blob types as well as different pricing tiers. This is beneficial for organizations that have different access requirements and application needs.

Read about managing unstructured data in hybrid architectures next.

Nahla Davies
Nahla Davies
Nahla Davies is a software developer and writer. Before devoting her work full time to technical writing, she managed—among other intriguing things—to serve as a lead programmer at an Inc. 5,000 experiential branding organization whose clients include Samsung, Time Warner, Netflix, and Sony.

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