Hidden Treasures

There’s that annoying feeling when, just as you’ve solved a problem that you’ve been working on for days, you realize the solution has caused a problem somewhere else. While working with a pair of early adopters of Windows 2000, this happened to me twice. In both cases happenstance led me to investigate some of Windows 2000’s most obscure updates: the improvements to NT File System (NTFS) 5.0.

Like gems hidden away from the noise and bright lights of the other new Windows 2000 features, the improvements made to NTFS aren’t obvious at first. But I believe they will become an important part of how managers keep the cost of storage system management declining.

The best-known improvement is NTFS 5.0's ability to invoke per user quotas. What little attention improvements to NTFS received generally surrounds disk quotas. While support for quotas is welcome by ISPs, it’s not the most far-reaching improvement in NTFS.

At first, disk quotas may seem like a tool an administrator can use to control how much disk space an individual user can consume. In practice, quotas are seldom established in that way. This is partly because enforcing limits using quotas means system administrators have to spend endless amounts of time explaining quota policies and enforcement to annoyed users and executives. Besides, traditional storage is cheap. What disk quotas really provide is an early warning system for administrators watching for unusual patterns of consumption or software problems whose symptoms include strange disk utilization patterns.

Beyond quotas, I was stunned when I discovered Microsoft had finally made it possible to have a mass storage device on a small system without requiring a drive letter. This long overdue improvement to Windows is based on a new NTFS feature called volume mount points. Besides being able to get rid of the Sesame Street-style limitation of 26 file system volumes, storage can now be added and distributed in an organization in a way that reflects its use rather than its physical structure or network topology.

Volume mount points are new directories in an established file system that point to additional storage units. Since NTFS is the source of this enhancement, it makes sense that volume mount points have to be established under an existing NTFS host. The volume being put into service, however, can use any file system Windows 2000 supports.

While quotas and volume mount points are unlikely to make anyone’s blood boil with excitement, they’re obvious and welcome improvements. Far less obvious, but much more far-reaching, is a new NTFS feature called reparse points. Never heard of it? I’m not surprised!

I’d wager that reparse points will be a feature of NTFS that few system administrators will ever take advantage of on their own. Yet the reparse point feature is destined to become the foundation for a new generation of storage management tools in Windows 2000.

Reparse points are built to allow a piece of software to intervene when any directory or file is opened. Every file system entry gets a system-controlled tag, called the reparse attribute, that keeps track of what software should be notified in case the directory or file is accessed. Thus, NTFS allows software developers to establish file system filters that can execute specific code when specific files are accessed.

This has profound implications for storage management. First, it has the potential to allow the system to change the look of the data as it is sent to a requesting application based on characteristics, such as who was requesting the data, or which application was asking for it. New accounting, encryption, and storage management tools will surely be built on the ability to intercept file and directory requests before data is actually delivered to the user.

I think storage management vendors are going to have a field day with reparse points -- one already has: Microsoft. The facility that makes volume mount points work is based on reparse point technology. Other vendors will extend the facilities that NTFS provides, not by having to write proprietary and hard-to-manage modules, but by coding reparse points and native NTFS file system filters.

We may not see new tools built on reparse points for a few months. It’s going to be a tool that few of us know about, but all of us -- whether we realize it or not -- should be glad we have it. The new, obscure features of NTFS are unlikely to be discovered by most of us -- yet will probably be more profound in their implications than some of the high-visibility items in Windows 2000. --Mark McFadden is a consultant and is communications director for the Commercial Internet eXchange (Washington). Contact him at mcfadden@cix.org.

Check out Mark McFadden's Web-only, bimonthly column, "Nothing but 'Net" at ENT's Web site: www.entmag.com.