Microsoft's goal is to make Windows the ideal networked storage platform. To fulfill this goal, Microsoft is assembling a storage "ecosystem" consisting of Microsoft Windows Storage Server 2003, Networked Attached Storage (NAS) partners, and partners that support Microsoft's Internet SCSI (iSCSI) driver and intelligent Storage Area Network (SAN) management efforts. Let's take a look at each of these areas, and I'll also provide an overview of where Windows Storage Server is today and where it's going.
Windows Storage Server 2003
Windows Storage Server is the newest member of the Windows Server 2003 family. Essentially, Windows Storage Server is a version of Windows 2003 that's optimized for file and print serving. Unlike Windows 2003, however, Windows Storage Server is available only to Microsoft's hardware partners, who use it as a base platform for building highly optimized NAS devices.
Windows Storage Server comes in two flavors: standard edition and enterprise edition. Standard edition supports NAS devices that don't require clustering or other high-end features. Enterprise edition supports high-end features such as multipath I/O, which lets Windows Storage Server use as many as 32 paths between the storage device and the servers that are attached to it. Multipath I/O also lets you provide for load balancing and failover in NICs that connect to a Windows Storage Server NAS device. In addition, enterprise edition supports enhanced clustering with as many as eight nodes of failover clustering and supports high-end NAS hardware that has more than four CPUs.
A Features Rundown
Windows Storage Server includes such Windows 2003 technologies as Microsoft Volume Shadow Copy Service (VSS) and Virtual Disk Service (VDS). Windows Storage Server is headless: You manage Windows Storage Server NAS devices from a browser or through Windows 2000 Server Terminal Services. All third-party utilities that run on Windows 2003 will run on Windows Storage Server.
Each partner that bundles Windows Storage Server with its products must qualify for the Designed for Windows logo by passing rigorous testing in Microsoft's Windows Hardware Quality Labs (WHQL). The WHQL tests and qualifies systems and device/driver combinations according to the Designed for Windows Logo Program requirements. The Designed for Windows Logo Program helps consumer and enterprise customers identify products that deliver a high-quality Windows experience.
More than 20 OEMs have licensed Windows Storage Server—Table 1 lists most of these OEMs. According to IDC, Windows Storage Server has already captured almost 50 percent of the NAS market share, making Windows the industry-standard platform for NAS devices. The fact that Windows Storage Server is the dominant NAS OS and that it's available from many vendors ensures that you'll find a solution to your specific storage situation at a competitive price and that your storage management utilities will work on the product you buy.
Beyond the base platform, Microsoft includes two key technologies in Windows Storage Server: VSS and VDS. You can think of VSS as the technology that enables intelligent snapshots and VDS as the technology that enables intelligent SAN management. Let's look at VSS first.
A snapshot is a point-in-time copy of a data set. Snapshots can be generated by either software or hardware providers; VSS supports both. Many SAN products include a hardware-based snapshot provider that's highly optimized to the vendor's specific platform. Such highly tuned hardware takes snapshots of large data sets in a fraction of the time that a software provider requires. Table 2 lists SAN vendors that offer hardware snapshot providers that support VSS.
When a Windows Storage Server NAS device uses a hardware-based snapshot provider to connect to a SAN, VSS can initiate a snapshot from the device without a storage administrator having to touch the SAN. In a Microsoft demonstration of this capability, VSS completed a hardware-replication snapshot of a 1.2TB database on a SAN in 1 minute.
Windows Storage Server includes its own software-based VSS snapshot provider, which allows as many as 512 point-in-time read-only snapshots (i.e., 64 snapshots per volume). Most administrators use Windows Storage Server's built-in snapshot provider to initiate snapshots of file-server data at predefined intervals.
A new trend in networked storage is to add snapshot support to applications and storage utilities. When an application is snapshot aware, it can help produce a clean snapshot of application-specific data. Say that your backup application needs a clean snapshot of a Microsoft Exchange Server 2003 mail store. The backup application asks VSS to initiate a snapshot. VSS alerts Exchange 2003 to flush its cache and hold pending changes, then initiates the snapshot of the mail store and returns the snapshot to the backup application. Because Exchange 2003 is snapshot aware, it can assist the backup application in creating an intelligent snapshot of the mail store. All major backup-software vendors, including Aelita Software (which was recently acquired by Quest Software), CommVault Systems, Computer Associates (CA), Dantz Development, EMC, HP, IBM, LEGATO Software, UltraBac Software, and VERITAS Software, now support VSS and can use it to create snapshots.
Because multiple snapshots can consume large amounts of disk space, you need to be able to manage them efficiently. Shadow copy management applications let you create, move, and manage shadow copies across any SAN-aware Windows 2003 device. Table 3 lists available shadow copy management applications.
Intelligent SAN Management
Microsoft also wants to make Windows the best platform for managing SANs. Windows Storage Server includes support for iSCSI—support that's important for compatibility when using a Windows Storage Server NAS device as a gateway to an iSCSI SAN or attaching Windows 2003 to an iSCSI SAN. To enable Windows Storage Server to redirect file-server requests to an attached iSCSI SAN, you need to download and install the free Microsoft iSCSI Software Initiator driver from http://www.microsoft.com/downloads/details.aspx?familyid=12cb3c1a-15d6-4585-b385-befd1319f825&displaylang=en. Independent hardware vendors can qualify their iSCSI hardware components for use with Windows through the Designed for Windows Logo Program. Table 4 lists the companies that have thus far qualified their products.
Like VSS, VDS provides a management interface for third-party hardware providers that support volume and disk management on third-party storage devices. For example, consider a situation in which you execute a VSS hardware-based snapshot on a SAN. By using VDS, you could change the snapshot LUN from read-only on the SAN to read-write, unmask the LUN to another server, and perform other volume and disk management operations. Although VDS executes on an attached SAN device, Windows Storage Server initiates all of VDS's functionality. Table 5 lists third-party VDS hardware providers.
You can think of VDS as being like ODBC in its early days. Early versions of ODBC supported only a small subset of the available SQL database engines. After several revisions, however, ODBC (and its successor technologies) now provides access to more than 80 percent of the functionality of most database engines and gives programmers the flexibility to support multiple database engines without changing the underlying application.
Similarly, VDS will develop over time to support most SAN management functionality. Then, Microsoft will be able to develop a standardized Web-based UI that will let administrators control most SAN functionality without having to learn the proprietary management UI that ships with each SAN. When Windows administrators can manage a SAN without having to learn a new technology, they will adopt SANs much more quickly. Ease-of-use, a low learning curve, and the lower cost of iSCSI-based SANs are the ingredients necessary for rapid adoption of mid-to-low-priced SANs.
Good News for Windows Administrators
In January 2004, IDC announced that more than half of all storage devices shipped in the second half of 2003 were networked storage devices. This announcement marked a significant turning point from the dominance of Direct Attached Storage (DAS) servers. And with Windows as the dominant OS for NAS devices, it's only a matter of time before Windows will be the dominant management UI for SANs as well. This is good news for Windows administrators, who can leverage their existing skills to manage tomorrow's future networked storage solutions.