• Sidebar: Lowering the Cost of iSCSI SAN Boot
• Sidebar: When Is NAS Appropriate?
• Chart: Four Windows Storage Server Editions

Network attached storage (NAS) devices running Windows Storage Server 2003 R2, a special version of Windows Server tailored for file serving, are now available from five hardware vendors. The inclusion of Windows SharePoint Services (WSS) gives Storage Server 2003 R2 more functionality than its predecessor or traditional NAS devices. Other improvements increase Storage Server's suitability for branch offices and yield storage capacity and performance greater than equivalent devices running Windows Server 2003 R2. However, Storage Server devices are not necessarily cheaper or even simpler than Windows Server equivalents, yet impose certain restrictions that could limit a customer's options.

In related news, Microsoft announced technology for hardware manufacturers that will allow Windows Server or Windows Storage Server computers to boot from iSCSI-based storage area network (SAN) storage using inexpensive network interface cards instead of the more expensive iSCSI host bus adapters. (For more information about iSCSI boot support, see the sidebar "Lowering the Cost of iSCSI SAN Boot".)

Specializing Windows Server for File Storage

NAS servers give other servers or workstations access over a network to pools of disk storage using a network file-sharing protocol, such as the Server Message Block (SMB) or the Network File System (NFS) protocols. The disk storage can be connected directly to the NAS server (direct attached storage, or DAS), or connected to the NAS server via a SAN. (For more discussion of when NAS is a good storage solution, see the sidebar "When Is NAS Appropriate?".)

In 2000, Microsoft began partnering with hardware vendors to offer NAS servers based on the Windows 2000 Server OS (called Windows-Powered NAS at the time.) Unlike the pioneering devices from competitor Network Appliance, which use a proprietary OS and file system designed specifically for serving files over the network, Microsoft decided to adapt Windows for the NAS OS role. This approach has many advantages even though it typically results in lower performance for equivalent processing power and data transfer capabilities, and may not provide certain highly specialized features such as disk volume replication to a disaster recovery site. Using the Windows OS dramatically reduces the amount of custom code the OEM needs to write, takes advantage of Windows' vast device driver library, and transfers most of the responsibility for fixing bugs and security vulnerabilities from the NAS device vendor to Microsoft. All of this allows Microsoft's hardware partners to offer NAS devices at much lower prices than proprietary NAS solutions.

Windows Storage Server is a special OEM-only edition of Windows Server. After Microsoft released Windows Server 2003 R2 in early 2006, it shipped the corresponding Windows Storage Server 2003 R2 in four editions, each with different sets of features. Three of these editions (Express, Workgroup, and Standard) are based on Windows Server 2003 R2 Standard Edition, and the other is based on Enterprise Edition. (For a table indicating the features in each edition, see the chart "Four Windows Storage Server Editions".)

This product segmentation is twice that of its predecessor, Windows Storage Server 2003, which came in only two editions—Standard and Enterprise—that mapped to the equivalent feature sets of the Windows Server 2003 Standard and Enterprise Editions.

The Storage Server editions of Windows deviate from the normal Windows Server OS in three key ways:

• Storage Server is specially tuned and licensed for the file-sharing and print-serving role (at the expense of reduced versatility for other functions)
• Some services not directly related to NAS and print-serving functions have been removed, such as Active Directory (AD), DNS, and DHCP (Storage Server can still be a member server in an AD domain and use Access Control Lists [ACLs] containing AD computers, users, and security groups to grant access to resources such as files, directories, and printers)
• Some editions of Storage Server can have features that are not included with Windows Server.

The Storage Server OEM ships the OS preinstalled and partially preconfigured on hardware that can range from a simple low-end server with DAS to a sophisticated multiserver cluster connected to a SAN-based storage array. These high-end NAS offerings typically include special features such as dynamic storage expansion or replication to an array at another site. While the low-end offerings provide relatively few advantages over simply buying Windows Server preinstalled on a server, Storage Server on high-end offerings eliminates some of the pain and risk that results when customers have to integrate and configure complex hardware and software on their own.

Because Storage Server is running the Windows Server OS, customers can install normal versions of Windows utility products, such as management agents, backup agents, and antivirus products, on it.

Unlike Windows Server, connecting to a Windows Storage Server device does not require the user's PC or connecting server to have a Windows Server Client Access License (CAL). However, because most organizations will already be authenticating users and computers with a Windows Server AD domain controller, which requires Windows Server per-user CALs, Microsoft's claim of "no CAL required" for Windows Storage Server is somewhat misleading. The only time this could be a significant benefit is when the Windows Storage Server device is used strictly to provide storage to non-Windows servers or Windows application servers that are not members of a Windows domain. This scenario requires administrators to manually configure and maintain local user accounts and passwords on the Storage Server device to authenticate and authorize the connecting servers.

New Features in R2

The enhancements to Windows Server 2003 R2 over that of its processor Windows Server 2003 were fairly modest, and a similar comparison applies to Windows Storage Server 2003 R2 and its predecessor Windows Storage Server 2003. The new Windows Storage Server 2003 R2 features and enhancements fall into three groups: those inherited from Windows Server 2003, those inherited from Windows Server 2003 R2, and those exclusive to Windows Storage Server 2003 R2.

Features Inherited from Windows Server 2003

Even though Windows Storage Server 2003 was based on Windows Server 2003, two features from that OS were left out. They are now included in Windows Storage Server 2003 R2.

64-bit support. A 64-bit version of Windows Storage Server 2003 R2 is now available on servers equipped with x64 processors. By supporting more memory, the 64-bit support allows Storage Server 2003 R2 devices to support more connections and higher workloads.

Windows SharePoint Services (WSS). Although WSS—Microsoft's Web-based collaboration solution for document and data sharing—is a free feature pack for Windows Server 2003, it was not included with Windows Storage Server 2003, and customers of that product are not licensed to install WSS on a Storage Server device. However, Windows Storage Server 2003 R2 includes WSS and SQL Server Express 2005, a free version of SQL Server 2005 that WSS uses for storing data.

Microsoft added WSS to allow (and even encourage) Storage Server customers to store files in WSS document libraries rather than on server file shares. Doing so gives customers certain document management capabilities, including versioning, controlled check-in/check-out, controlled publishing to SharePoint Portal Services, and the ability to tag documents with metadata such as owner, descriptions, and other custom attributes. This last feature makes it easier for users to organize and find documents. With WSS, the documents are stored in the SQL Server database, so to harness the NAS device's vast disk storage to store SharePoint documents, SQL Server must be running on the NAS server.

Although WSS may be a welcome addition for some customers, it transforms what was a simple NAS device into a more complex application server that takes more skill to set up, tune, and maintain. For example, tuning the OS to run SQL Server requires OS settings that are different from those for a dedicated file-and-print server, and SQL Server requires special backup techniques. Also, since WSS is a Web application, the device has to run Internet Information Services (IIS) as well. Lastly, each organization will have to configure and customize the WSS Web Parts to meet its particular needs.

Features Inherited from Windows Server 2003 R2

Some new features in Windows Server 2003 R2, such as Active Directory Federation Services, are not applicable to Storage Server because it is not a general purpose server and cannot be configured as an AD domain controller. However, most of the other new Windows Server 2003 R2 features carry over.

Distributed File System. Windows Storage Server 2003 R2 gets the completely revamped Distributed File System (DFS), which consist of two parts: DFS Namespaces (DFS-N) and DFS Replication (DFS-R). DFS-N allows administrators to create a single "virtual" directory tree from multiple physical servers. DFS-R allows organizations to replicate files and directories among servers and is designed to do this efficiently over WANs.

Together, these two services make it possible for an IT organization to build a system that eliminates the need for users to know which servers their data reside on. Each user will automatically be directed to a server on their local LAN when they access a shared file, and changes to the file will be replicated to the other servers participating in the DFS-R system. If a server is down, DFS-N will automatically reroute the user to an alternate server that has a replica of the user's file. (Unlike Windows Cluster services, the simpler DFS-based redundancy solution applies only to closed files that have finished replicating.)

Windows Storage Server 2003 R2 NAS servers can participate in DFS systems with Windows Server 2003 R2 file servers, but not with earlier versions of Windows Server that use an older implementation of DFS.

File System Resource Manager (FSRM) is a Microsoft Management Console (MMC) snap-in, plus several new background services. FSRM allows system administrators to manage disk storage quotas on Windows Server 2003 R2 file servers and Windows Storage Server 2003 R2 NAS devices, control what kinds of files may be stored on them, and generate reports on disk usage.

Print Management Console (PMC) is a new MMC snap-in that gives administrators a single interface for managing all print servers (and their attached printers) within an organization, including print services running on Windows Storage Server 2003 R2 devices, rather than requiring administrators to connect to each print server. The PMC's one-to-many remote management makes it easier for IT departments to manage branch servers configured for the print server role.

Storage Manager for SANs. If the Windows Storage Server 2003 R2 device stores its files on a SAN, administrators can use the Storage Manager for SANs MMC snap-in to ease configuration and management of SAN disk volumes, as long as the SAN storage arrays support the Virtual Disk Service (VDS), a storage management API introduced in Windows Server 2003. VDS gives Microsoft and third-party management applications a standard, hardware-independent way to manage any storage device or SAN component that has an associated VDS provider.

Services for UNIX (SFU) improvements. Windows Storage Server 2003 R2 supports the Network File System (NFS) to serve files to Unix and Linux computers, and its NFS implementation benefits from SFU improvements in Windows Server 2003 R2. The new SFU allows Windows Server 2003 R2 domain controllers to host the Network Information System (NIS) directory, synchronize NIS and AD passwords, and map Unix/Linux user IDs and group IDs to AD users and groups. This integration makes it much easier to set the access control lists (ACLs) on Windows Server 2003 R2 and Windows Storage Server 2003 R2 files and folders, and have those ACLs apply properly to the user accounts of the Unix and Linux computers connecting to it.

New Features Exclusive to Windows Storage Server 2003 R2

Windows Storage Server 2003 R2 has several features not currently found in Windows Server 2003 R2 (although these features could appear in a future release of Windows Server).

Single Instance Storage (SIS) allows Windows Storage Server 2003 R2 (Standard and Enterprise Editions only) to designate disk volumes such that any file written to them is stored only once on the hard disk. Duplicate files saved to a different location on the same volume are replaced with "sparse link" entries that point to the real files in the SIS store—a concept similar to a shortcut, except that a sparse link looks and acts exactly like a normal file. However, when a link is deleted, SIS simply decrements a reference count to the real file. When all links have been deleted, the file is deleted from the SIS store. Sparse links include file metadata, such as time stamps, ACLs, and tags such as title or subject. The fact that ACLs are tied to the link rather than the real file means that a user might have access to the file going through one sparse link while being denied through a different sparse link.

SIS can result in significant disk space savings, particularly in user home directories, where many different users often keep copies of the exact same files. Microsoft's IT department claims that SIS reduced storage volumes by 40%.

SIS was first introduced in Windows Server 2000 for use by the Remote Installation Service (RIS) to reduce the disk space requirements of storing many different system configurations, but this is the first time SIS has been supported for general purpose storage. Because of the unique way that SIS stores files, backup programs must be SIS-capable. Currently CA ARCServe, CommVault Galaxy, and Symantec (Veritas) Backup Exec can properly back up Windows Storage Servers that use SIS.

Improved file system indexing. The indexing service on Windows Storage Server 2003 R2 is now better suited for use on a NAS server where files are constantly changing. The indexing service in Windows Server 2003 R2 and all earlier versions went offline to rebuild the index every time a change was made to a file, which effectively made the indexing service useless on a file server. However, on Windows Storage Server 2003 R2 the index isn't rebuilt until it accrues a larger batch of changes, and the old index stays available while a new one is being built. Although the index is not guaranteed to be up-to-date in real time, it is good enough to be a boon to users. This enhancement means that users searching shares on a Windows Storage Server 2003 R2 device using the Windows Explorer search function on Windows 2000 or later can find the files they are looking for much faster. Furthermore, the Windows Storage Server 2003 R2 indexing engine now includes parsers (called iFilters) for Office document formats, and administrators can install additional parsers for third-party formats, such as Adobe PDF or WinZip ZIP formats.

WSS, which stores its content in SQL Server rather than the file system, does not use this indexing service.

Performance tuned for file sharing. Microsoft claims that by tuning Windows Storage Server 2003 R2's OS and networking protocols for the specific needs of serving files, it has improved file sharing performance by 25% to 30% over that of Windows Server 2003 R2 running on identical hardware.

Target Customers

Although Microsoft and its Windows Storage Server 2003 R2 partners claim that these dedicated devices can be set up more quickly than the same hardware running Windows Server 2003 R2, this one-time savings is fairly minor compared to other factors, and neither Microsoft nor its OEM partners account for the time it will take an administrator to configure WSS or configure the devices into a larger DFS system.

Furthermore, the price of one of these dedicated Storage Servers is not necessarily cheaper than the do-it-yourself option with Windows Server 2003 R2. For example, a model of Dell's simplest Windows Storage Server 2003 R2 device (based on its PowerEdge 830 server) costs US$1,117, a slight savings from US$1,398 for Windows Server 2003 R2 on nearly identical hardware. However, a high-end Windows Storage Server 2003 R2 device from Hewlett-Packard (HP) (based on its Proliant DL585 server) goes for US$14,434, well over the US$12,336 cost of nearly the same hardware with Windows Server 2003 R2 Enterprise Edition. (In both cases, the values of bundled CALs were subtracted from the Windows Server prices, and neither of the HP products included the cost of the necessary back-end SAN storage, which would be identical for both configurations.)

The main advantage of the Windows Storage Server 2003 R2 NAS platform over that of Windows Server 2003 R2 on the same hardware really boils down to the performance tuning and the storage efficiency gained by SIS. With a Standard or Enterprise Edition of Windows Storage Server 2003 R2 NAS device, a customer can either support more users on a NAS device of a given size and speed or it can use a smaller, cheaper device to support its file storage needs.

However, prospective buyers of Windows Storage Server 2003 R2 devices must weigh these benefits against several caveats related to freedom and flexibility. Although they can install the types of utility programs mentioned earlier and can install critical Microsoft patches using tools such as Windows Update, Microsoft Update, Automatic Update, or Systems Management Server, the Windows Storage Server 2003 R2 license agreement prohibits installing other applications. Customers are not even free to install Microsoft service packs, feature packs, or updates to the bundled applications unless obtained from the OEM. For example, when the next release of Windows SharePoint Services ships late this year, Windows Storage Server 2003 R2 device customers cannot upgrade to it unless the OEM decides to offer and support it.

Probably the biggest caveat is that these devices are not upgradeable. Unlike Windows Server 2003 R2 customers who can buy upgrade rights to the next release—code-named Windows Longhorn Server and due to ship in the second half of 2007—through Microsoft's Software Assurance program, there is no similar program that grants customers upgrade rights to a future Longhorn-based release of Windows Storage Server. Because Storage Server is an OEM-only product, customers do not even have the option of purchasing upgrades to the next release of Storage Server from Microsoft. They could purchase full Longhorn Server licenses and repurpose the devices to become general purpose servers, but doing so will likely void their existing OEM support agreements.

Availability and Resources

Windows Storage Server 2003 R2 devices are currently available from Dell, HP, IBM, LeftHand Networks, and Tacit Networks on a plethora of different hardware configurations and different editions of Windows Storage Server 2003 R2.

Microsoft's support for SANs and networked storage is described in "Driving Down the Cost of SANs" on page 3 of the May 2005 Update and at www.microsoft.com/windowsserversystem/storage.

A full description of the new features in Windows Server 2003 R2, on which Windows Storage Server 2003 R2 is based, can be found in the Mar. 2006 Research Report, "Evaluating Windows Server 2003 R2."