Azure Storage is one of the most heavily tested domains on the AZ-900 exam. Understanding how Blob storage, Azure Files, Queue storage, and Table storage differ — and when to use each — is essential for passing. This guide breaks down every storage concept Microsoft expects you to know, from redundancy options like LRS and GRS to hot, cool, and archive access tiers.
Whether you are studying for the first time or doing a final review before exam day, this page gives you a structured, exam-focused breakdown of Azure Storage fundamentals. Pair it with our complete AZ-900 study guide for full coverage of all exam domains.
Azure storage begins with a storage account, which acts as a unique namespace for all your storage data accessible over HTTP or HTTPS. For the AZ-900 exam, you need to understand the two primary account types: Standard general-purpose v2 (GPv2) and Premium. GPv2 accounts support Blob, File, Queue, and Table storage and are backed by magnetic drives (HDD). Premium accounts use solid-state drives (SSD) and are optimized for low-latency scenarios.
A storage account name must be globally unique across all of Azure, between 3 and 24 characters, and can only contain lowercase letters and numbers. This uniqueness requirement is because the storage account name becomes part of the endpoint URL — for example, https://mystorageaccount.blob.core.windows.net. Understanding this structure helps you answer questions about how Azure identifies and routes storage requests.
Storage accounts also determine which redundancy options are available to you. Not all redundancy configurations are available for all account types or regions, which is an important nuance for the exam. For a broader view of how storage fits into the Azure ecosystem, see our cloud concepts guide and our dedicated networking guide for how virtual networks interact with storage endpoints.
Blob (Binary Large Object) storage is Azure's solution for storing massive amounts of unstructured data — things like images, videos, documents, backups, and log files. Blobs are organized into containers within a storage account, and each blob can be up to 190.7 TB in size. There are three blob types you must know for the AZ-900 exam:
Blob storage supports three access tiers — hot, cool, and archive — which control how data is stored and how much it costs to access. This tiering system is one of the most tested topics in the storage domain. We cover tiers in detail in the access tiers section below.
Azure Files provides fully managed file shares in the cloud, accessible via the industry-standard Server Message Block (SMB) protocol and the Network File System (NFS) protocol. Unlike Blob storage which uses a flat namespace, Azure Files uses a hierarchical file system — making it a drop-in replacement for on-premises file servers.
Key use cases for Azure Files include lift-and-shift migrations of applications that rely on file shares, shared configuration files across multiple virtual machines, and diagnostic data like logs and crash dumps. Azure File Sync can extend Azure Files into on-premises environments by caching frequently accessed files locally while storing everything in Azure. For tips on passing the exam, see our AZ-900 pass guide.
Azure Queue Storage provides reliable messaging for asynchronous communication between application components. Messages can be up to 64 KB in size, and a queue can contain millions of messages. Queue storage decouples components so they can scale independently — for example, a web front-end adds work items to a queue, and a background worker processes them at its own pace.
Azure Table Storage is a NoSQL key-attribute store for semi-structured data. It stores data as collections of entities, each with up to 252 custom properties. Table storage is cost-effective and well-suited for storing flexible datasets like user data for web applications, address books, or device information for IoT scenarios. For the AZ-900 exam, know that Table storage is part of Cosmos DB's table API offering as well.
Redundancy is among the most frequently tested storage topics on the AZ-900 exam. Azure automatically stores multiple copies of your data to protect against hardware failures, network outages, and natural disasters. You choose the redundancy option when you create your storage account, and it determines how and where your data is replicated.
There are four redundancy configurations to know:
A key exam distinction: GRS and GZRS also have read-access variants (RA-GRS and RA-GZRS) that allow you to read from the secondary region endpoint at any time — not just during a failover. The secondary endpoint URL has a -secondary suffix appended to the account name.
Azure Blob storage offers three access tiers that let you balance storage costs against access costs. The AZ-900 exam expects you to know the trade-off for each tier:
Tiers can be set at the blob level (not the account level), so you can have hot and cool blobs coexisting in the same container. Lifecycle management policies can automatically move blobs between tiers based on rules you define — for example, moving blobs to cool after 30 days and to archive after 90 days.
Azure Virtual Machines use managed disks as their block-level storage volumes. Managed disks are backed by Azure Storage and are fully managed by Azure — you don't have to manage storage accounts for them. There are four disk types:
For the AZ-900 exam, you are not expected to memorize IOPS figures, but you should know the general positioning: Ultra Disk is top-tier, Premium SSD is production-grade, Standard SSD balances cost and performance, and Standard HDD is lowest cost for non-critical use.