Azure Files and Table Storage

What it is

Besides blobs, Azure Storage offers two more services the exam covers. Azure Files gives you managed file shares that behave like a network drive. Azure Table Storage is a simple, low cost NoSQL store for entities made of keys and attributes.

Both live in a storage account, next to Blob Storage.

How it works

Azure Files

Azure Files provides fully managed file shares in the cloud. You reach them with the standard file sharing protocols, SMB and NFS, so existing applications work without being rewritten. Shares can be mounted at the same time from Windows, Linux and macOS machines, in Azure or on premises.

SMB suits Windows, Linux and macOS clients. NFS is for Linux clients, which suits Linux workloads and containers. You can also reach a share through the REST interface.

Common uses include:

• Replacing or extending file servers. A department share moves to Azure and nothing changes for users.
• Lift and shift of applications that expect a shared drive for configuration or data.
• Shared storage for containers or virtual machines.

Azure File Sync keeps a Windows file server and an Azure file share in step. Frequently used files are cached on the local server, while the full set stays in the cloud.

Azure Table Storage

Table Storage holds structured NoSQL data. It is a key and attribute store with a schemaless design. A table holds entities, and each entity is a set of properties, a little like a row, except that entities in one table can have different properties.

Every entity is identified by two keys.

Queries are fast when they use the keys. Table Storage has no joins, no foreign keys and no stored procedures, and it is not a relational database. It is typically cheaper than a traditional SQL database for similar volumes of data, which makes it a good fit for flexible datasets such as user data for web apps, address books and device information.

PartitionKey: "Lisbon"   RowKey: "device-0042"   Model: "T-800"   Firmware: "2.1"

Moving up to Cosmos DB for Table

Applications written for Table Storage can use Azure Cosmos DB for Table with the same table model. It adds higher throughput, single digit millisecond latency and global distribution, at a higher price.

Choosing between the storage services

A worked scenario

A company has a legacy application that reads its settings from a shared drive. It cannot be changed, so the team creates an Azure file share and mounts it on the application servers over SMB. A separate part of the system stores device status records, each looked up by device code. Those records have no relationships and need only fast key access, so Table Storage keeps cost low.

Using a share

Mounting a file share gives users a drive letter on Windows or a mount point on Linux. SMB uses TCP port 445, so a network that blocks that port cannot reach a share directly, and a VPN or private connection is the usual answer. Access can use a storage account key or identity based authentication with Microsoft Entra Domain Services or on premises Active Directory.

Tiers and redundancy

Azure Files has performance options, from premium shares on solid state drives for demanding workloads, to standard shares for general use, with transaction optimized, hot and cool choices. Like Blob Storage it supports redundancy choices such as LRS, ZRS and GRS, and share snapshots let you recover earlier versions of files.

Table Storage queries

Designing the keys well is therefore the main skill. For device data you might use the region as the PartitionKey and the device code as the RowKey, so that a lookup of one device is a point query and all devices in a region are one partition.

Table Storage compared with Cosmos DB for Table