Choose by the data interface
Azure storage questions often contain an interface clue. Object storage, a shared file system and a virtual-machine disk are different workload requirements even when each stores bytes.
Object data
Choose Azure Blob Storage for unstructured objects accessed through HTTP-based APIs: images, video, documents, logs, backups and analytics data.
Shared files
Choose Azure Files when multiple systems need a managed file share through supported file-sharing protocols and applications expect folders and paths.
VM block storage
Choose Azure managed disks for operating-system and data disks attached to Azure virtual machines.
AZ-900 decision rule
Object or URL/API access: Blob Storage. Mounted shared file system: Azure Files. Persistent disk for a VM: Managed Disks. The interface comes before the pricing tier or redundancy choice.
Compare the core storage choices
A storage account can expose several services, but each service has its own interface and workload fit. A managed disk is presented as a separate managed Azure resource rather than a file share mounted by many clients.
Redundancy and access tiers solve different problems
Redundancy controls where Azure maintains copies of data. Locally redundant storage keeps copies within one physical location in the primary region. Zone-redundant storage distributes copies across availability zones in the primary region. Geo-redundant options add replication to a secondary region; read-access variants can permit reads from the secondary endpoint.
Blob access tiers optimize storage and access costs based on usage patterns. Frequently accessed data typically fits a hot tier. Infrequently accessed data can fit cooler online tiers, subject to retention and access-cost trade-offs. Archive is an offline tier with retrieval delay and is unsuitable when immediate access is required.
Keep the questions separate
Ask first: Which storage interface fits? Next: How quickly and often is the data accessed? Finally: Where must copies exist to meet durability and availability requirements?
Worked scenario: media application and finance system
A company stores product images, exports reports for a legacy finance application, runs a database on an Azure VM and archives compliance records.
- Store product images as objects in Blob Storage and deliver them through an application or content-delivery design.
- Use Azure Files for report exchange when the finance application requires a mounted shared-file interface.
- Use managed disks for the VM operating system and database data volumes, with a performance tier selected for the workload.
- Evaluate a cooler Blob tier for old compliance objects only when expected access frequency, retrieval time and minimum-retention economics fit.
- Select storage redundancy from the business durability, availability and regional-recovery requirements—not from the data format alone.
- Add identity, least-privilege access, encryption, private networking where required, monitoring, backup and tested recovery. Replication is not a substitute for every backup or recovery need.
Common AZ-900 mistakes
- Selecting Azure Files merely because the stored objects have filenames.
- Selecting Blob Storage when a legacy application requires a mounted shared drive.
- Treating managed disks as general shared file storage for many clients.
- Confusing a Blob access tier with a redundancy option.
- Choosing Archive for data that must be read immediately.
- Assuming geo-replication alone creates an end-to-end disaster-recovery plan.
- Choosing the cheapest storage tier without considering retrieval, transaction and retention trade-offs.
- Ignoring identity, network exposure and data-protection requirements.
AZ-900 practice checks with explanations
An application stores millions of product photographs and reads them through web requests. Which service?
Best answer: Azure Blob Storage. The data is unstructured object content accessed through an HTTP-oriented interface.
Several servers must mount the same managed cloud file share. Which service?
Best answer: Azure Files. The decisive clue is the shared file-system interface.
A new Azure VM needs a persistent operating-system disk. Which service?
Best answer: Azure Managed Disks, which provides block storage for Azure VMs.
A company wants copies across availability zones in one Azure region. Which concept should it evaluate?
Best answer: Zone-redundant storage. This is a replication decision, separate from choosing Blob Storage, Azure Files or an access tier.
Frequently asked questions
When should I choose Azure Blob Storage?
Choose Blob Storage for large amounts of unstructured object data such as images, video, logs, documents, backups and analytics data that applications access through HTTP-based APIs.
What is Azure Files used for?
Azure Files provides managed file shares that can be mounted by cloud or on-premises systems using supported file-sharing protocols. It is useful when applications expect a shared file-system interface.
What is an Azure managed disk?
A managed disk is block storage designed for Azure virtual machines. Azure manages the underlying storage account while the disk is attached to a VM as an operating-system or data disk.
Are Hot, Cool and Archive access tiers redundancy options?
No. Access tiers optimize Blob Storage cost for expected access frequency and retrieval needs. Redundancy options determine how copies of data are replicated for durability and availability.
Does geo-redundant storage automatically make every application resilient?
No. Storage replication protects copies of stored data, but application resilience also requires suitable service configuration, failover behavior, identity, networking, monitoring, backup and recovery planning.
Official Microsoft references
- Current AZ-900 study guide
- Describe Azure storage services
- Introduction to Azure Storage
- Azure Storage redundancy
- Blob access tiers
Confirm current service, region, performance and pricing details before making production decisions. ITCertPath uses original learning scenarios and does not reproduce confidential Microsoft exam questions.