Section 5.7. Windows-Powered NAS Devices and Snapshots | Inside Windows Storage: Server Storage Technologies for Windows 2000, Windows Server 2003 and Beyond

5.7 Windows-Powered NAS Devices and Snapshots

Microsoft offers a version of Windows NT that is sometimes referred to as "Embedded NT" and more often as the Server Appliance Kit, or SAK. This offering is based on Windows 2000, which does not have a volume shadow copy service. For the benefit of original equipment manufacturers that use the SAK to build NAS devices, Microsoft has licensed a snapshot solution and included it in the SAK. This snapshot product is the Persistent Storage Manager (PSM) from Columbia Data Products. This section provides a quick overview of PSM architecture and functionality.

PSM architecture is shown in Figure 5.9. PSM has a user mode component that facilitates snapshot management, including initiation and scheduling of snapshot creation. The snapshots are created via the services of the PSM filter driver that is layered over the disk class driver as shown in Figure 5.9.

Figure 5.9. Persistent Storage Manager Architecture

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PSM offers the ability to create multiple snapshots and manage them. Snapshots can be created according to a schedule, and older snapshots may be saved or written over. One can also "mount" the older snapshots and use them for backup or other purposes. Each snapshot has a date and timestamp associated with it.

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