Network File System overview

Applies to: Windows Server 2016, Windows Server 2012 R2, Windows Server 2012

This topic describes the Network File System role service and features included with the File and Storage Services server role in Windows Server. Network File System (NFS) provides a file sharing solution for enterprises that have heterogeneous environments that include both Windows and non-Windows computers.

Feature description

Using the NFS protocol, you can transfer files between computers running Windows and other non-Windows operating systems, such as Linux or UNIX.

NFS in Windows Server includes Server for NFS and Client for NFS. A computer running Windows Server can use Server for NFS to act as a NFS file server for other non-Windows client computers. Client for NFS allows a Windows-based computer running Windows Server to access files stored on a non-Windows NFS server.

Windows and Windows Server versions

Windows supports multiple versions ofthe NFS client and server, depending on operating system version and family.

Operating Systems	NFS Server Versions	NFS Client Versions
Windows 7, Windows 8.1, Windows 10	N/A	NFSv2, NFSv3
Windows Server 2008, Windows Server 2008 R2	NFSv2, NFSv3	NFSv2, NFSv3
Windows Server 2012, Windows Server 2012 R2, Windows Server 2016, Windows Server 2019	NFSv2, NFSv3, NFSv4.1	NFSv2, NFSv3

Practical applications

Here are some ways you can use NFS:

• Use a Windows NFS file server to provide multi-protocol access to the same file share over both SMB and NFS protocols from multi-platform clients.
• Deploy a Windows NFS file server in a predominantly non-Windows operating system environment to provide non-Windows client computers access to NFS file shares.
• Migrate applications from one operating system to another by storing the data on file shares accessible through both SMB and NFS protocols.

New and changed functionality

New and changed functionality in Network File System includes support for the NFS version 4.1 and improved deployment and manageability. For information about functionality that is new or changed in Windows Server 2012, review the following table:

Feature/functionality	New or updated	Description
NFS version 4.1	New	Increased security, performance, and interoperability compared to NFS version 3.
NFS infrastructure	Updated	Improves deployment and manageability, and increases security.
NFS version 3 continuous availability	Updated	Improves continuous availability on NFS version 3 clients.
Deployment and manageability improvements	Updated	Enables you to easily deploy and manage NFS with new Windows PowerShell cmdlets and a new WMI provider.

NFS version 4.1

NFS version 4.1 implements all of the required aspects, in addition to some of the optional aspects, of RFC 5661:

• Pseudo file system, a file system that separates physical and logical namespace and is compatible with NFS version 3 and NFS version 2. An alias is provided for the exported file system, which is part of the pseudo file system.
• Compound RPCs combine relevant operations and reduce chattiness.
• Sessions and session trunking enables just one semantic and allows continuous availability and better performance while utilizing multiple networks between NFS 4.1 clients and the NFS Server.

NFS infrastructure

Improvements to the overall NFS infrastructure in Windows Server 2012 are detailed below:

• The Remote Procedure Call (RPC)/External Data Representation (XDR) transport infrastructure, powered by the WinSock network protocol, is available for both Server for NFS and Client for NFS. This replaces Transport Device Interface (TDI), offers better support, and provides better scalability and Receive Side Scaling (RSS).
• The RPC port multiplexer feature is firewall-friendly (less ports to manage) and simplifies deployment of NFS.
• Auto-tuned caches and thread pools are resource management capabilities of the new RPC/XDR infrastructure that are dynamic, automatically tuning caches and thread pools based on workload. This completely removes the guesswork involved when tuning parameters, providing optimal performance as soon as NFS is deployed.
• New Kerberos privacy implementation and authentication options with the addition of Kerberos privacy (Krb5p) support along with the existing krb5 and krb5i authentication options.
• Identity Mapping Windows PowerShell module cmdlets make it easier to manage identity mapping, configure Active Directory Lightweight Directory Services (AD LDS), and set up UNIX and Linux passwd and flat files.
• Volume mount point lets you access volumes mounted under an NFS share with NFS version 4.1.
• The Port Multiplexing feature supports the RPC port multiplexer (port 2049), which is firewall-friendly and simplifies NFS deployment.

NFS version 3 continuous availability

NFS version 3 clients can have fast and transparent planned failovers with more availability and reduced downtime. The failover process is faster for NFS version 3 clients because:

• The clustering infrastructure now allows one resource per network name instead of one resource per share, which significantly improves resources’ failover time.
• Failover paths within an NFS server are tuned for better performance.
• Wildcard registration in an NFS server is no longer required, and the failovers are more fine-tuned.
• Network Status Monitor (NSM) notifications are sent out after a failover process, and clients no longer need to wait for TCP timeouts to reconnect to the failed over server.

Note that Server for NFS supports transparent failover only when manually initiated, typically during planned maintenance. If an unplanned failover occurs, NFS clients lose their connections. Server for NFS also doesn’t have any integration with the Resume Key filter. This means that if a local app or SMB session attempts to access the same file that an NFS client is accessing immediately after a planned failover, the NFS client might lose its connections (transparent failover wouldn’t succeed).

Deployment and manageability improvements

Deploying and managing NFS has improved in the following ways:

• Over forty new Windows PowerShell cmdlets make it easier to configure and manage NFS file shares. For more information, see NFS Cmdlets in Windows PowerShell.
• Identity mapping is improved with a local flat file mapping store and new Windows PowerShell cmdlets for configuring identity mapping.
• The Server Manager graphical user interface is easier to use.
• The new WMI version 2 provider is available for easier management.
• The RPC port multiplexer (port 2049) is firewall-friendly and simplifies deployment of NFS.

Server Manager information

In Server Manager — or the newer Windows Admin Center — use the Add Roles and Features Wizard to add the Server for NFS role service (under the File and iSCSI Services role). For general information about installing features, see Install or Uninstall Roles, Role Services, or Features. Server for NFS tools include the Services for Network File System MMC snap-in to manage the Server for NFS and Client for NFS components. Using the snap-in, you can manage the Server for NFS components installed on the computer. Server for NFS also contains several Windows command-line administration tools:

• Mount mounts a remote NFS share (also known as an export) locally and maps it to a local drive letter on the Windows client computer.
• Nfsadmin manages configuration settings of the Server for NFS and Client for NFS components.
• Nfsshare configures NFS share settings for folders that are shared using Server for NFS.
• Nfsstat displays or resets statistics of calls received by Server for NFS.
• Showmount displays mounted file systems exported by Server for NFS.
• Umount removes NFS-mounted drives.

NFS in Windows Server 2012 introduces the NFS module for Windows PowerShell with several new cmdlets specifically for NFS. These cmdlets provide an easy way to automate NFS management tasks. For more information, see NFS cmdlets in Windows PowerShell.

Additional information

The following table provides additional resources for evaluating NFS.

Scale-Out File Server for application data overview

Applies to: Windows Server 2019, Windows Server 2016, Windows Server 2012 R2, Windows Server 2012

Scale-Out File Server is designed to provide scale-out file shares that are continuously available for file-based server application storage. Scale-out file shares provides the ability to share the same folder from multiple nodes of the same cluster. This scenario focuses on how to plan for and deploy Scale-Out File Server.

You can deploy and configure a clustered file server by using either of the following methods:

• Scale-Out File Server for application data This clustered file server feature was introduced in Windows Server 2012, and it lets you store server application data, such as Hyper-V virtual machine files, on file shares, and obtain a similar level of reliability, availability, manageability, and high performance that you would expect from a storage area network. All file shares are simultaneously online on all nodes. File shares associated with this type of clustered file server are called scale-out file shares. This is sometimes referred to as active-active. This is the recommended file server type when deploying either Hyper-V over Server Message Block (SMB) or Microsoft SQL Server over SMB.
• File Server for general use This is the continuation of the clustered file server that has been supported in Windows Server since the introduction of Failover Clustering. This type of clustered file server, and therefore all the shares associated with the clustered file server, is online on one node at a time. This is sometimes referred to as active-passive or dual-active. File shares associated with this type of clustered file server are called clustered file shares. This is the recommended file server type when deploying information worker scenarios.

Scenario description

With scale-out file shares, you can share the same folder from multiple nodes of a cluster. For instance, if you have a four-node file server cluster that is using Server Message Block (SMB) Scale-Out, a computer running Windows Server 2012 R2 or Windows Server 2012 can access file shares from any of the four nodes. This is achieved by leveraging new Windows Server Failover Clustering features and the capabilities of the Windows file server protocol, SMB 3.0. File server administrators can provide scale-out file shares and continuously available file services to server applications and respond to increased demands quickly by simply bringing more servers online. All of this can be done in a production environment, and it is completely transparent to the server application.

Key benefits provided by Scale-Out File Server in include:

• Active-Active file shares. All cluster nodes can accept and serve SMB client requests. By making the file share content accessible through all cluster nodes simultaneously, SMB 3.0 clusters and clients cooperate to provide transparent failover to alternative cluster nodes during planned maintenance and unplanned failures with service interruption.
• Increased bandwidth. The maximum share bandwidth is the total bandwidth of all file server cluster nodes. Unlike previous versions of Windows Server, the total bandwidth is no longer constrained to the bandwidth of a single cluster node; but rather, the capability of the backing storage system defines the constraints. You can increase the total bandwidth by adding nodes.
• CHKDSK with zero downtime. CHKDSK in Windows Server 2012 is significantly enhanced to dramatically shorten the time a file system is offline for repair. Clustered shared volumes (CSVs) take this one step further by eliminating the offline phase. A CSV File System (CSVFS) can use CHKDSK without impacting applications with open handles on the file system.
• Clustered Shared Volume cache. CSVs in Windows Server 2012 introduces support for a Read cache, which can significantly improve performance in certain scenarios, such as in Virtual Desktop Infrastructure (VDI).
• Simpler management. With Scale-Out File Server, you create the scale-out file servers, and then add the necessary CSVs and file shares. It is no longer necessary to create multiple clustered file servers, each with separate cluster disks, and then develop placement policies to ensure activity on each cluster node.
• Automatic rebalancing of Scale-Out File Server clients. In Windows Server 2012 R2, automatic rebalancing improves scalability and manageability for scale-out file servers. SMB client connections are tracked per file share (instead of per server), and clients are then redirected to the cluster node with the best access to the volume used by the file share. This improves efficiency by reducing redirection traffic between file server nodes. Clients are redirected following an initial connection and when cluster storage is reconfigured.

In this scenario

The following topics are available to help you deploy a Scale-Out File Server:

When to use Scale-Out File Server

You should not use Scale-Out File Server if your workload generates a high number of metadata operations, such as opening files, closing files, creating new files, or renaming existing files. A typical information worker would generate a lot of metadata operations. You should use a Scale-Out File Server if you are interested in the scalability and simplicity that it offers and if you only require technologies that are supported with Scale-Out File Server.

The following table lists the capabilities in SMB 3.0, the common Windows file systems, file server data management technologies, and common workloads. You can see whether the technology is supported with Scale-Out File Server, or if it requires a traditional clustered file server (also known as a file server for general use).

Technology Area	Feature	General Use File Server Cluster	Scale-Out File Server
SMB	SMB Continuous Availability (*)	Yes	Yes
SMB	SMB Multichannel	Yes	Yes
SMB	SMB Direct	Yes	Yes
SMB	SMB Encryption	Yes	Yes
SMB	SMB Transparent failover	Yes (if continuous availability is enabled)	Yes
File System	NTFS	Yes	NA
File System	Resilient File System (ReFS)	Recommended with Storage Spaces Direct	Recommended with Storage Spaces Direct
File System	Cluster Shared Volume File System (CSV)	NA	Yes
File Management	BranchCache	Yes	No
File Management	Data Deduplication (Windows Server 2012)	Yes	No
File Management	Data Deduplication (Windows Server 2012 R2)	Yes	Yes (VDI only)
File Management	DFS Namespace (DFSN) root server root	Yes	No
File Management	DFS Namespace (DFSN) folder target server	Yes	Yes
File Management	DFS Replication (DFSR)	Yes	No
File Management	File Server Resource Manager (Screens and Quotas)	Yes	No
File Management	File Classification Infrastructure	Yes	No
File Management	Dynamic Access Control (claim-based access, CAP)	Yes	No
File Management	Folder Redirection	Yes	Not recommended
File Management	Offline Files (client side caching)	Yes	Not recommended
File Management	Roaming User Profiles	Yes	Not recommended
File Management	Home Directories	Yes	Not recommended
File Management	Work Folders	Yes	No
NFS	NFS Server	Yes	No
Applications	Hyper-V	Not recommended	Yes
Applications	Microsoft SQL Server	Not recommended	Yes

Folder Redirection, Offline Files, Roaming User Profiles, or Home Directories generate a large number of writes that must be immediately written to disk (without buffering) when using continuously available file shares, reducing performance as compared to general purpose file shares. Continuously available file shares are also incompatible with File Server Resource Manager and PCs running Windows XP. Additionally, Offline Files might not transition to offline mode for 3-6 minutes after a user loses access to a share, which could frustrate users who aren’t yet using the Always Offline mode of Offline Files.

Practical applications

Scale-Out File Servers are ideal for server application storage. Some examples of server applications that can store their data on a scale-out file share are listed below:

• The Internet Information Services (IIS) Web server can store configuration and data for Web sites on a scale-out file share. For more information, see Shared Configuration.
• Hyper-V can store configuration and live virtual disks on a scale-out file share. For more information, see Deploy Hyper-V over SMB.
• SQL Server can store live database files on a scale-out file share. For more information, see Install SQL Server with SMB file share as a storage option.
• Virtual Machine Manager (VMM) can store a library share (which contains virtual machine templates and related files) on a scale-out file share. However, the library server itself can’t be a Scale-Out File Server—it must be on a stand-alone server or a failover cluster that doesn’t use the Scale-Out File Server cluster role.

If you use a scale-out file share as a library share, you can use only technologies that are compatible with Scale-Out File Server. For example, you can’t use DFS Replication to replicate a library share hosted on a scale-out file share. It’s also important that the scale-out file server have the latest software updates installed.

To use a scale-out file share as a library share, first add a library server (likely a virtual machine) with a local share or no shares at all. Then when you add a library share, choose a file share that’s hosted on a scale-out file server. This share should be VMM-managed and created exclusively for use by the library server. Also make sure to install the latest updates on the scale-out file server. For more information about adding VMM library servers and library shares, see Add profiles to the VMM library. For a list of currently available hotfixes for File and Storage Services, see Microsoft Knowledge Base article 2899011.

Some users, such as information workers, have workloads that have a greater impact on performance. For example, operations like opening and closing files, creating new files, and renaming existing files, when performed by multiple users, have an impact on performance. If a file share is enabled with continuous availability, it provides data integrity, but it also affects the overall performance. Continuous availability requires that data writes through to the disk to ensure integrity in the event of a failure of a cluster node in a Scale-Out File Server. Therefore, a user that copies several large files to a file server can expect significantly slower performance on continuously available file share.

Features included in this scenario

The following table lists the features that are part of this scenario and describes how they support it.