Overview of Disk Management

Hard disk storage has been the usual long-term storage method for modern computers, from the mainframe to the desktop, and that's not likely to change, even considering the richer storage options that have been added to Windows 2000. This section looks at each of the new facilities.

RAID

RAID (redundant array of independent disks) is a term used to describe a technique that has gone from an esoteric high-end solution to a normal assumption on most servers. Seven or eight years ago, RAID was mostly unheard of, although the original paper defining RAID was written in 1988. Until recently, most server systems relied on expensive, higher quality hard disks—backed up frequently. Backups are still crucial, but now you can use one form or another of RAID to provide substantial protection from hard disk failure. Moreover, this protection costs much less than those big server drives did.

RAID can be implemented at a software or hardware level. When it is implemented at the hardware level, the hardware vendor provides an interface to administer the arrays and the drivers to support the various operating systems it might need to work with. Although there are advantages to using a hardware RAID solution, it's not cheap.

Windows 2000 includes an excellent and flexible implementation of RAID levels 0, 1, and 5 in software. It doesn't cover all of the possibilities by any means, but it is certainly sufficient for many purposes.

Disk Administration Enhancements

The task of disk management in Windows 2000 brings not only a brand new interface, based on the Microsoft Management Console (MMC), but also a whole new set of capabilities (Figure 15-1). Anyone who has spent much time with Windows NT will probably not miss the old Disk Administrator at all.

The MMC's Disk Management snap-in for managing your physical disks is divided into two panes. By default, the top pane shows the drive letters (volumes) associated with the local disks and gives their properties and status, and the bottom pane has a graphical representation organized by physical drive. It can be used as a stand-alone snap-in or as part of the Computer Management console, shown in Figure 15-2.

Figure 15-1. Disk Management with an MMC interface.

Figure 15-2. The Computer Management console and the Disk Management snap-in.

Hardware RAID

Disk Management provides an excellent software RAID solution, but hardware RAID is also now widely available, from either the original server vendor or from third parties, and it provides substantial advantages over software RAID. Hardware RAID solutions range from a simple RAID controller to fully integrated, stand-alone subsystems. Their features vary, as does their cost, but all claim to provide superior performance and reliability over a simple software RAID solution such as that included in Windows 2000. In general, they do. Some of the advantages that they can offer include the following:

• Hot-swap and hot-spare drives, allowing for virtually instantaneous replacement of failed drives
• Integrated disk caching for improved disk performance
• A separate, dedicated system that handles all processing, for improved overall performance
• Increased flexibility and additional RAID levels, such as RAID-10 (also called RAID 0+1), a combination of striping (RAID-0) and mirroring (RAID-1) that provides for fast read and write disk access with full redundancy

Not all hardware RAID systems provide all of these features, but all have the potential to improve the overall reliability and performance of your hard disk subsystem. As such, they should definitely be considered for any mission-critical server.

Remote Management

The new Disk Management snap-in in Windows 2000 Server lets you manage not only the local hard disks but also drives on other computers running Windows 2000 or Microsoft Windows XP, enabling the administrator to manage disk tasks and space allocations from a workstation without having to sit at the machine that is being administered. This capability is a boon for remote site management and—using the MMC—makes it easy to delegate authority and administrative responsibilities for a group of computers to others without having to give them full administrative privileges.

Dynamic Disks

The other major feature that Disk Management adds in Windows 2000 and later versions is the concept of dynamic disks. By converting a disk to a dynamic disk, you give Disk Management the ability to manage it in new ways, without requiring a reboot in most cases. You can extend a disk volume, span a volume across multiple physical disks, stripe the volume for improved performance, mirror it, or add it to a RAID-5 array—all from the MMC and all without a reboot, once the disk is converted to a dynamic disk. The initial creation or conversion of the first of your basic disks to a dynamic disk requires a reboot, unfortunately, but once you've gotten over that hurdle, you'll breeze through the remaining tasks. When combined with the new remote management functionality, dynamic disks give the system administrator powerful tools for managing the type and configuration of hard disk storage across the enterprise.