Blob Storage vs Azure Files in Azure

Core access model differences

Azure Blob Storage is object storage. Objects (files, images, videos, backups, logs) are stored in containers as flat-namespace blobs. Access is via the Azure Storage REST API, Azure SDKs, AzCopy, the Azure CLI, or Azure Storage Explorer. There is no filesystem semantics — you cannot “open” a blob for writing, append a line to it using a file path, or rename it atomically without an API call. Blob Storage scales to petabytes and is the foundation of Azure Data Lake Storage (Gen2) with hierarchical namespace.

Azure Files is a managed file share. It uses standard SMB (Server Message Block) and NFS (Network File System) protocols that any Windows, Linux, or macOS client can mount. Once mounted, it behaves like a local drive — applications that write to C:\App\Logs\ can write to Z:\App\Logs\ without code changes. Azure Files provides POSIX file system semantics including file locking, rename, and directory traversal.

Comparison across key dimensions

Performance tiers

Blob Storage offers two performance tiers:

• Standard: HDD-backed, suitable for most object storage workloads. Hot tier ($0.018/GB) is for frequently accessed data; Cool ($0.01/GB) for infrequently accessed; Archive (~$0.001/GB) for long-term cold storage.
• Premium Block Blobs: SSD-backed, approximately $0.10/GB/month but with significantly lower latency (single-digit milliseconds for reads/writes). Appropriate for high-throughput workloads — video streaming, ML training data access, real-time logging.

Azure Files offers two performance tiers:

• Standard (Transaction Optimised / Hot / Cool): HDD-backed. Standard SMB share at ~$0.06/GB/month. Suitable for general file sharing and lift-and-shift scenarios.
• Premium (SSD): Provisioned IOPS model — you provision the share size (minimum 100 GiB) and pay for provisioned capacity at ~$0.26/GiB/month plus IOPS. Premium Azure Files is required for NFS protocol and for latency-sensitive workloads (databases that use file shares, container persistent volume claims needing fast IO).

Lifecycle management: Blob Storage advantage

Blob Storage includes a lifecycle management policy engine that can automatically move or delete blobs based on age, last-modified date, or last-accessed date. A policy that moves blobs older than 30 days to Cool tier and older than 180 days to Archive tier can reduce storage costs significantly for log data, backup files, and archival content.

{
  "rules": [
    {
      "name": "tiering-rule",
      "type": "Lifecycle",
      "definition": {
        "filters": { "blobTypes": ["blockBlob"], "prefixMatch": ["logs/"] },
        "actions": {
          "baseBlob": {
            "tierToCool": { "daysAfterModificationGreaterThan": 30 },
            "tierToArchive": { "daysAfterModificationGreaterThan": 180 },
            "delete": { "daysAfterModificationGreaterThan": 730 }
          }
        }
      }
    }
  ]
}

Azure Files does not have an equivalent lifecycle policy system. Files can be tiered between Hot, Cool, and Transaction Optimised share-level tiers manually, but there is no per-file automatic tiering to an Archive-equivalent tier.

When to use Blob Storage

• Storing user-uploaded content — profile images, documents, videos — accessed via application code or CDN
• Application log archiving and audit trail storage
• Data lake for analytics — Azure Data Lake Storage Gen2 is built on Blob Storage with hierarchical namespace
• Static website hosting — HTML, CSS, JavaScript assets served directly from Blob Storage
• Machine learning training data sets and model artefacts
• VM backup images, database backups, snapshots
• Any workload where data is accessed programmatically via API rather than mounted as a filesystem

When to use Azure Files

• Lift-and-shift of applications that use on-premises file shares — applications that read/write to UNC paths or SMB drives
• Shared application configuration files that multiple VMs or containers need to access simultaneously as a mounted path
• Application development environments where shared code repositories or build artefacts are accessed via network drive
• Azure Kubernetes Service persistent volumes that need to be shared across multiple pods simultaneously (ReadWriteMany access mode)
• Home directories and profile shares for Azure Virtual Desktop deployments