Improving Storage Management

Because of the increasing use of SANs, Windows Server 2008 includes many features for working with SANs and handling storage management in general. These features include the following:

• Volume Shadow Copy Service (VSS): VSS allows administrators to create pointin- time copies of volumes and individual files called snapshots. This makes it possible to back up these items while files are open and applications are running and to restore them to a specific point in time. VSS also makes it possible to create point-in-time copies of documents on shared folders. These copies are called shadow copies.
  Note: Users can recover their own files when VSS is enabled. After you configure shadow copy, point-in-time backups of documents contained in the designated shared folders are created automatically, and users can quickly recover files that have been deleted or unintentionally altered as long as the Shadow Copy Client has been installed on their computer.
• Virtual Disk Service (VDS): VDS makes it possible for storage devices from multiple vendors to interoperate. To do this, VDS provides application programming interfaces (APIs) that management tools and storage hardware can use, allowing for a unified interface for managing storage devices from multiple vendors and making it easier for administrators to manage a mixed-storage environment.
• Volume automounting: Volume automounting makes it possible to better manage the way volumes are mounted. By using the Mountvol command, administrators can turn off volume automounting. By using volume mount points, administrators can mount volumes to empty NTFS folders, giving the volumes a drive path rather than a drive letter. This means it is easier to mount and unmount volumes, particularly with SANs.
• Multipath I/O: Multipath I/O supports SAN connectivity by establishing multiple sessions or connections to storage devices. Using multipath I/O, you can configure as many as 32 separate physical paths to external storage devices that can be used simultaneously and load balanced if necessary. The purpose of having multiple paths is to have redundancy and possibly increased throughput. If you have multiple host bus adapters as well, you improve the chances of recovery from a path failure. However, if a path failure occurs, there might be a short period of time when the drives on the SAN aren't accessible.
• Distributed File System (DFS): DFS makes it possible to create a single directory tree that includes multiple file servers and their file shares. The DFS tree can contain more than 5,000 shared folders in a domain environment (or 50,000 shared folders on a stand-alone server), located on different servers, allowing users to find files or folders distributed across the enterprise easily. DFS directory trees can also be published in the Active Directory directory service so that they are easy to search.
  DFS Supports Multiple Roots and Closest-Site Selection
  Windows Server 2008 supports multiple DFS roots and closest-site selection. The capability to host multiple DFS roots allows you to consolidate and reduce the number of servers needed to maintain DFS. By using closest-site selection, DFS uses Active Directory site metrics to route a client to the closest available DFS server.
• File Replication Service (FRS): FRS makes it possible to synchronize data across the enterprise and is in fact the synchronization technology used by Active Directory. FRS works in conjunction with DFS to replicate data on file shares and automatically maintain synchronization of copies on multiple servers. FRS is capable of compressing replication traffic as well.

Windows Server 2008 has several command-line tools for managing local storage and storage replication services. These tools include the following:

• DiskPart: Used to manage disks, partitions, and volumes. It is the command-line counterpart to the Disk Management tool and also includes features not found in the graphical user interface (GUI) tool, such as the capability to extend partitions on basic disks.
• Dfscmd: Used to create DFS volumes by mapping DFS paths to server paths and manage replicas on DFS volumes.
• Dfsdiag: Used to perform troubleshooting and diagnostics for DFS.
• Dfsradmin: Used to manage and monitor DFS replication throughout the enterprise. You'll use this tool for troubleshooting and diagnosing problems as well. This tool replaces Health_Chk and the other tools it worked with.
• Dfsrmig: Used to manually migrate the Sysvol from FRS replication to DFS replication.
  Note: When a domain is running at Windows 2000 mixed, Windows 2000 native, or Windows Server 2003 functional level, domain controllers replicate the Sysvol using File Replication Service (FRS). When a domain is running at Windows Server 2008 functional level, domain controllers replicate the Sysvol using Distributed File System (DFS).
• Dfsutil: Used to configure DFS, back up and restore DFS directory trees (namespaces), copy directory trees, and troubleshoot DFS.
• Fsutil: Used to get detailed drive information and perform advanced file system maintenance. You can manage sparse files, reparse points, disk quotas, and other advanced features of NTFS.
• Vssadmin: Used to view and manage the Volume Shadow Copy Service and its configuration.