Planning for an Azure Files deployment

Azure Files can be deployed in two main ways: by directly mounting the serverless Azure file shares or by caching Azure file shares on-premises using Azure File Sync. Which deployment option you choose changes the things you need to consider as you plan for your deployment.

  • Direct mount of an Azure file share: Since Azure Files provides either Server Message Block (SMB) or Network File System (NFS) access, you can mount Azure file shares on-premises or in the cloud using the standard SMB or NFS clients available in your OS. Because Azure file shares are serverless, deploying for production scenarios does not require managing a file server or NAS device. This means you don't have to apply software patches or swap out physical disks.

  • Cache Azure file share on-premises with Azure File Sync: Azure File Sync enables you to centralize your organization's file shares in Azure Files, while keeping the flexibility, performance, and compatibility of an on-premises file server. Azure File Sync transforms an on-premises (or cloud) Windows Server into a quick cache of your Azure SMB file share.

This article primarily addresses deployment considerations for deploying an Azure file share to be directly mounted by an on-premises or cloud client. To plan for an Azure File Sync deployment, see Planning for an Azure File Sync deployment.

Available protocols

Azure Files offers two industry-standard protocols for mounting Azure file share: the Server Message Block (SMB) protocol and the Network File System (NFS) protocol. Azure Files enables you to pick the file system protocol that is the best fit for your workload. Azure file shares do not support both the SMB and NFS protocols on the same file share, although you can create SMB and NFS Azure file shares within the same storage account. NFS 4.1 is currently only supported within new FileStorage storage account type (premium file shares only).

With both SMB and NFS file shares, Azure Files offers enterprise-grade file shares that can scale up to meet your storage needs and can be accessed concurrently by thousands of clients.

Feature SMB NFS
Supported protocol versions SMB 3.1.1, SMB 3.0, SMB 2.1 NFS 4.1
Recommended OS
  • Windows 10, version 21H1+
  • Windows Server 2019+
  • Linux kernel version 5.3+
Linux kernel version 4.3+
Available tiers Premium, transaction optimized, hot, and cool Premium
Billing model Provisioned capacity
File system semantics Win32 POSIX
Authentication Identity-based authentication (Kerberos), shared key authentication (NTLMv2) Host-based authentication
Authorization Win32-style access control lists (ACLs) UNIX-style permissions
Case sensitivity Case insensitive, case preserving Case sensitive
Deleting or modifying open files With lock only Yes
File sharing Windows sharing mode Byte-range advisory network lock manager
Hard link support Not supported Supported
Symbolic link support Not supported Supported
Optionally internet accessible Yes (SMB 3.0+ only) No
Supports FileREST Yes Subset:

Management concepts

Azure file shares are deployed into storage accounts, which are top-level objects that represent a shared pool of storage. This pool of storage can be used to deploy multiple file shares, as well as other storage resources such as blob containers, queues, or tables. All storage resources that are deployed into a storage account share the limits that apply to that storage account. For current storage account limits, see Azure Files scalability and performance targets.

There are two main types of storage accounts you will use for Azure Files deployments:

  • General purpose version 2 (GPv2) storage accounts: GPv2 storage accounts allow you to deploy Azure file shares on standard/hard disk-based (HDD-based) hardware. In addition to storing Azure file shares, GPv2 storage accounts can store other storage resources such as blob containers, queues, or tables.
  • FileStorage storage accounts: FileStorage storage accounts allow you to deploy Azure file shares on premium/solid-state disk-based (SSD-based) hardware. FileStorage accounts can only be used to store Azure file shares; no other storage resources (blob containers, queues, tables, etc.) can be deployed in a FileStorage account. Only FileStorage accounts can deploy both SMB and NFS file shares.

There are several other storage account types you may come across in the Azure portal, PowerShell, or CLI. Two storage account types, BlockBlobStorage and BlobStorage storage accounts, cannot contain Azure file shares. The other two storage account types you may see are general purpose version 1 (GPv1) and classic storage accounts, both of which can contain Azure file shares. Although GPv1 and classic storage accounts may contain Azure file shares, most new features of Azure Files are available only in GPv2 and FileStorage storage accounts. We therefore recommend to only use GPv2 and FileStorage storage accounts for new deployments, and to upgrade GPv1 and classic storage accounts if they already exist in your environment.

When deploying Azure file shares into storage accounts, we recommend:

  • Only deploying Azure file shares into storage accounts with other Azure file shares. Although GPv2 storage accounts allow you to have mixed purpose storage accounts, since storage resources such as Azure file shares and blob containers share the storage account's limits, mixing resources together may make it more difficult to troubleshoot performance issues later on.

  • Paying attention to a storage account's IOPS limitations when deploying Azure file shares. Ideally, you would map file shares 1:1 with storage accounts, however this may not always be possible due to various limits and restrictions, both from your organization and from Azure. When it is not possible to have only one file share deployed in one storage account, consider which shares will be highly active and which shares will be less active to ensure that the hottest file shares don't get put in the same storage account together.

  • Only deploy GPv2 and FileStorage accounts and upgrade GPv1 and classic storage accounts when you find them in your environment.


To access an Azure file share, the user of the file share must be authenticated and have authorization to access the share. This is done based on the identity of the user accessing the file share. Azure Files integrates with three main identity providers:

  • On-premises Active Directory Domain Services (AD DS, or on-premises AD DS): Azure storage accounts can be domain joined to a customer-owned, Active Directory Domain Services, just like a Windows Server file server or NAS device. You can deploy a domain controller on-premises, in an Azure VM, or even as a VM in another cloud provider; Azure Files is agnostic to where your domain controller is hosted. Once a storage account is domain-joined, the end user can mount a file share with the user account they signed into their PC with. AD-based authentication uses the Kerberos authentication protocol.
  • Azure Active Directory Domain Services (Azure AD DS): Azure AD DS provides a Microsoft-managed domain controller that can be used for Azure resources. Domain joining your storage account to Azure AD DS provides similar benefits to domain joining it to a customer-owned Active Directory. This deployment option is most useful for application lift-and-shift scenarios that require AD-based permissions. Since Azure AD DS provides AD-based authentication, this option also uses the Kerberos authentication protocol.
  • Azure storage account key: Azure file shares may also be mounted with an Azure storage account key. To mount a file share this way, the storage account name is used as the username and the storage account key is used as a password. Using the storage account key to mount the Azure file share is effectively an administrator operation, since the mounted file share will have full permissions to all of the files and folders on the share, even if they have ACLs. When using the storage account key to mount over SMB, the NTLMv2 authentication protocol is used.

For customers migrating from on-premises file servers, or creating new file shares in Azure Files intended to behave like Windows file servers or NAS appliances, domain joining your storage account to Customer-owned Active Directory is the recommended option. To learn more about domain joining your storage account to a customer-owned Active Directory, see Azure Files Active Directory overview.

If you intend to use the storage account key to access your Azure file shares, we recommend using service endpoints as described in the Networking section.


Azure file shares are accessible from anywhere via the storage account's public endpoint. This means that authenticated requests, such as requests authorized by a user's logon identity, can originate securely from inside or outside of Azure. In many customer environments, an initial mount of the Azure file share on your on-premises workstation will fail, even though mounts from Azure VMs succeed. The reason for this is that many organizations and internet service providers (ISPs) block the port that SMB uses to communicate, port 445. To see the summary of ISPs that allow or disallow access from port 445, go to TechNet.

To unblock access to your Azure file share, you have two main options:

  • Unblock port 445 for your organization's on-premises network. Azure file shares may only be externally accessed via the public endpoint using internet safe protocols such as SMB 3.x and the FileREST API. This is the easiest way to access your Azure file share from on-premises since it doesn't require advanced networking configuration beyond changing your organization's outbound port rules, however, we recommend you remove legacy and deprecated versions of the SMB protocol, namely SMB 1.0. To learn how to do this, see Securing Windows/Windows Server and Securing Linux.

  • Access Azure file shares over an ExpressRoute or VPN connection. When you access your Azure file share via a network tunnel, you are able to mount your Azure file share like an on-premises file share since SMB traffic does not traverse your organizational boundary.

Although from a technical perspective it's considerably easier to mount your Azure file shares via the public endpoint, we expect most customers will opt to mount their Azure file shares over an ExpressRoute or VPN connection. Mounting with these options is possible with both SMB and NFS shares. To do this, you will need to configure the following for your environment:

  • Network tunneling using ExpressRoute, Site-to-Site, or Point-to-Site VPN: Tunneling into a virtual network allows accessing Azure file shares from on-premises, even if port 445 is blocked.
  • Private endpoints: Private endpoints give your storage account a dedicated IP address from within the address space of the virtual network. This enables network tunneling without needing to open on-premises networks up to all the of the IP address ranges owned by the Azure storage clusters.
  • DNS forwarding: Configure your on-premises DNS to resolve the name of your storage account ( for the public cloud regions) to resolve to the IP address of your private endpoints.


Azure Files supports multiple network routing options. The default option, Microsoft routing, works with all Azure Files configurations. The internet routing option does not support AD domain join scenarios or Azure File Sync.

To plan for the networking associated with deploying an Azure file share, see Azure Files networking considerations.


Azure Files supports two different types of encryption: encryption in transit, which relates to the encryption used when mounting/accessing the Azure file share, and encryption at rest, which relates to how the data is encrypted when it is stored on disk.

Encryption in transit


This section covers encryption in transit details for SMB shares. For details regarding encryption in transit with NFS shares, see Security and networking.

By default, all Azure storage accounts have encryption in transit enabled. This means that when you mount a file share over SMB or access it via the FileREST protocol (such as through the Azure portal, PowerShell/CLI, or Azure SDKs), Azure Files will only allow the connection if it is made with SMB 3.x with encryption or HTTPS. Clients that do not support SMB 3.x or clients that support SMB 3.x but not SMB encryption will not be able to mount the Azure file share if encryption in transit is enabled. For more information about which operating systems support SMB 3.x with encryption, see our detailed documentation for Windows, macOS, and Linux. All current versions of the PowerShell, CLI, and SDKs support HTTPS.

You can disable encryption in transit for an Azure storage account. When encryption is disabled, Azure Files will also allow SMB 2.1, SMB 3.x without encryption, and unencrypted FileREST API calls over HTTP. The primary reason to disable encryption in transit is to support a legacy application that must be run on an older operating system, such as Windows Server 2008 R2 or older Linux distribution. Azure Files only allows SMB 2.1 connections within the same Azure region as the Azure file share; an SMB 2.1 client outside of the Azure region of the Azure file share, such as on-premises or in a different Azure region, will not be able to access the file share.

We strongly recommend ensuring encryption of data in-transit is enabled.

For more information about encryption in transit, see requiring secure transfer in Azure storage.

Encryption at rest

All data stored in Azure Files is encrypted at rest using Azure storage service encryption (SSE). Storage service encryption works similarly to BitLocker on Windows: data is encrypted beneath the file system level. Because data is encrypted beneath the Azure file share's file system, as it's encoded to disk, you don't have to have access to the underlying key on the client to read or write to the Azure file share. Encryption at rest applies to both the SMB and NFS protocols.

By default, data stored in Azure Files is encrypted with Microsoft-managed keys. With Microsoft-managed keys, Microsoft holds the keys to encrypt/decrypt the data, and is responsible for rotating them on a regular basis. You can also choose to manage your own keys, which gives you control over the rotation process. If you choose to encrypt your file shares with customer-managed keys, Azure Files is authorized to access your keys to fulfill read and write requests from your clients. With customer-managed keys, you can revoke this authorization at any time, but this means that your Azure file share will no longer be accessible via SMB or the FileREST API.

Azure Files uses the same encryption scheme as the other Azure storage services such as Azure Blob storage. To learn more about Azure storage service encryption (SSE), see Azure storage encryption for data at rest.

Data protection

Azure Files has a multi-layered approach to ensuring your data is backed up, recoverable, and protected from security threats.

Soft delete

Soft delete for file shares is a storage-account level setting that allows you to recover your file share when it is accidentally deleted. When a file share is deleted, it transitions to a soft deleted state instead of being permanently erased. You can configure the amount of time soft deleted data is recoverable before it's permanently deleted, and undelete the share anytime during this retention period.

We recommend turning on soft delete for most file shares. If you have a workflow where share deletion is common and expected, you may decide to have a short retention period or not have soft delete enabled at all.

For more information about soft delete, see Prevent accidental data deletion.


You can back up your Azure file share via share snapshots, which are read-only, point-in-time copies of your share. Snapshots are incremental, meaning they only contain as much data as has changed since the previous snapshot. You can have up to 200 snapshots per file share and retain them for up to 10 years. You can either manually take these snapshots in the Azure portal, via PowerShell, or command-line interface (CLI), or you can use Azure Backup. Snapshots are stored within your file share, meaning that if you delete your file share, your snapshots will also be deleted. To protect your snapshot backups from accidental deletion, ensure soft delete is enabled for your share.

Azure Backup for Azure file shares handles the scheduling and retention of snapshots. Its grandfather-father-son (GFS) capabilities mean that you can take daily, weekly, monthly, and yearly snapshots, each with their own distinct retention period. Azure Backup also orchestrates the enablement of soft delete and takes a delete lock on a storage account as soon as any file share within it is configured for backup. Lastly, Azure Backup provides certain key monitoring and alerting capabilities that allow customers to have a consolidated view of their backup estate.

You can perform both item-level and share-level restores in the Azure portal using Azure Backup. All you need to do is choose the restore point (a particular snapshot), the particular file or directory if relevant, and then the location (original or alternate) you wish you restore to. The backup service handles copying the snapshot data over and shows your restore progress in the portal.

For more information about backup, see About Azure file share backup.

Protect Azure Files with Microsoft Defender for Storage

Microsoft Defender for Storage provides an additional layer of security intelligence that generates alerts when it detects anomalous activity on your storage account, for example unusual access attempts. It also runs malware hash reputation analysis and will alert on known malware. You can configure Microsoft Defender for Storage at the subscription or storage account level via Microsoft Defender for Cloud.

For more information, see Introduction to Microsoft Defender for Storage.

Storage tiers

Azure Files offers four different tiers of storage, premium, transaction optimized, hot, and cool to allow you to tailor your shares to the performance and price requirements of your scenario:

  • Premium: Premium file shares are backed by solid-state drives (SSDs) and provide consistent high performance and low latency, within single-digit milliseconds for most IO operations, for IO-intensive workloads. Premium file shares are suitable for a wide variety of workloads like databases, web site hosting, and development environments. Premium file shares can be used with both Server Message Block (SMB) and Network File System (NFS) protocols.
  • Transaction optimized: Transaction optimized file shares enable transaction heavy workloads that don't need the latency offered by premium file shares. Transaction optimized file shares are offered on the standard storage hardware backed by hard disk drives (HDDs). Transaction optimized has historically been called "standard", however this refers to the storage media type rather than the tier itself (the hot and cool are also "standard" tiers, because they are on standard storage hardware).
  • Hot: Hot file shares offer storage optimized for general purpose file sharing scenarios such as team shares. Hot file shares are offered on the standard storage hardware backed by HDDs.
  • Cool: Cool file shares offer cost-efficient storage optimized for online archive storage scenarios. Cool file shares are offered on the standard storage hardware backed by HDDs.

Premium file shares are deployed in the FileStorage storage account kind and are only available in a provisioned billing model. For more information on the provisioned billing model for premium file shares, see Understanding provisioning for premium file shares. Standard file shares, including transaction optimized, hot, and cool file shares, are deployed in the general purpose version 2 (GPv2) storage account kind, and are available through pay as you go billing.

When selecting a storage tier for your workload, consider your performance and usage requirements. If your workload requires single-digit latency, or you are using SSD storage media on-premises, the premium tier is probably the best fit. If low latency isn't as much of a concern, for example with team shares mounted on-premises from Azure or cached on-premises using Azure File Sync, standard storage may be a better fit from a cost perspective.

Once you've created a file share in a storage account, you cannot move it to tiers exclusive to different storage account kinds. For example, to move a transaction optimized file share to the premium tier, you must create a new file share in a FileStorage storage account and copy the data from your original share to a new file share in the FileStorage account. We recommend using AzCopy to copy data between Azure file shares, but you may also use tools like robocopy on Windows or rsync for macOS and Linux.

File shares deployed within GPv2 storage accounts can be moved between the standard tiers (transaction optimized, hot, and cool) without creating a new storage account and migrating data, but you will incur transaction costs when you change your tier. When you move a share from a hotter tier to a cooler tier, you will incur the cooler tier's write transaction charge for each file in the share. Moving a file share from a cooler tier to a hotter tier will incur the cool tier's read transaction charge for each file in the share.

See Understanding Azure Files billing for more information.


Standard file shares with 100 TiB capacity have certain limitations.

  • Currently, only locally redundant storage (LRS) and zone redundant storage (ZRS) accounts are supported.
  • Once you enable large file shares, you cannot convert storage accounts to geo-redundant storage (GRS) or geo-zone-redundant storage (GZRS) accounts.
  • Once you enable large file shares, you can't disable it.


To protect the data in your Azure file shares against data loss or corruption, all Azure file shares store multiple copies of each file as they are written. Depending on the requirements of your workload, you can select additional degrees of redundancy. Azure Files currently supports the following data redundancy options:

  • Locally-redundant storage (LRS): With LRS, every file is stored three times within an Azure storage cluster. This protects against loss of data due to hardware faults, such as a bad disk drive. However, if a disaster such as fire or flooding occurs within the data center, all replicas of a storage account using LRS may be lost or unrecoverable.
  • Zone-redundant storage (ZRS): With ZRS, three copies of each file stored, however these copies are physically isolated in three distinct storage clusters in different Azure availability zones. Availability zones are unique physical locations within an Azure region. Each zone is made up of one or more data centers equipped with independent power, cooling, and networking. A write to storage is not accepted until it is written to the storage clusters in all three availability zones.
  • Geo-redundant storage (GRS): With GRS, you have two regions, a primary and secondary region. Files are stored three times within an Azure storage cluster in the primary region. Writes are asynchronously replicated to a Microsoft-defined secondary region. GRS provides six copies of your data spread between two Azure regions. In the event of a major disaster such as the permanent loss of an Azure region due to a natural disaster or other similar event, Microsoft will perform a failover and the secondary becomes the primary, serving all operations. Since the replication between the primary and secondary regions are asynchronous, in the event of a major disaster, data not yet replicated to the secondary region will be lost. You can also perform a manual failover of a geo-redundant storage account.
  • Geo-zone-redundant storage (GZRS): You can think of GZRS as if it were like ZRS but with geo-redundancy. With GZRS, files are stored three times across three distinct storage clusters in the primary region. All writes are then asynchronously replicated to a Microsoft-defined secondary region. The failover process for GZRS works the same as GRS.

Standard Azure file shares up to 5-TiB support all four redundancy types. Standard file shares larger than 5-TiB only support LRS and ZRS. Premium Azure file shares only support LRS and ZRS.

General purpose version 2 (GPv2) storage accounts provide two additional redundancy options that are not supported by Azure Files: read accessible geo-redundant storage, often referred to as RA-GRS, and read accessible geo-zone-redundant storage, often referred to as RA-GZRS. You can provision Azure file shares in storage accounts with these options set, however Azure Files does not support reading from the secondary region. Azure file shares deployed into read-accessible geo- or geo-zone redundant storage accounts will be billed as geo-redundant or geo-zone-redundant storage, respectively.


In many cases, you will not be establishing a net new file share for your organization, but instead migrating an existing file share from an on-premises file server or NAS device to Azure Files. Picking the right migration strategy and tool for your scenario is important for the success of your migration.

The migration overview article briefly covers the basics and contains a table that leads you to migration guides that likely cover your scenario.

Next steps