1.4 Registry Zen

Even if you're accustomed to using Windows, the Registry may sometimes seem like a New Orleans graveyard at midnight, full of strange shadows, half-glimpsed terrors, and legendary tales of misfortune. In this vein, I want to digress a little to talk about the philosophy behind the Registry, as well as the Zen of editing and using it.

First of all comes the obligatory scare tactic. Microsoft's documentation contains many warnings about the dire consequences that can result from editing the Registry if you aren't careful and knowledgeable. Instead of repeating these warnings, I'll offer one of my own, but just once, so you won't have to keep seeing it over and over.

The Registry is a key component of Windows 2000. If you remove a necessary key or change a key's value to an out-of-range value, some programs repair the damage automatically, but others fail spectacularly. Microsoft's Registry editors immediately make changes, so there's no backing out if you make a mistake. Please don't edit the Registry on your production machines until you've read Chapter 3, which explains how to recover from a damaged Registry.

You can think of the Registry like one of those self-service storage warehouses that have popped up across North America like sheet-metal mushrooms. If you've never seen one, let me briefly digress: these warehouses, which usually have catchy names such as "Public Storage" or "U-Store-It," are fenced compounds filled with long, low metal buildings. These buildings are segmented into individual garages. When you rent a space, you get the magic code that opens the outer gate, and you use your own lock to secure the unit you've rented. Once you've rented it, the space is yours to use as you wish (though you're not supposed to live in them or keep anything illegal or dangerous there).

Just like the local U-Store-It, every tenant of the Registry has its own individual space, where it can store anything under the sun. Access to that space is controlled both by the operating system and the tenant who created the keys. Also like the real-world equivalent, the landlord takes no responsibility for protecting what's in individual spaces; that's up to the renter (or application). That's where the analogy stops, though. In Windows 2000, Registry keys fall into three groups:

Keys you don't need to edit directly

Keys in this group have some other way to set their value; most control panels are nothing more than pretty interfaces that make it easy for you to change settings in the Registry without using a Registry editor. The Explorer's file types dialog box is another good example; all it does is display, and allows you to change, data in the HKEY_CLASSES_ROOT tree.

Keys you must edit directly

In the grand Microsoft tradition, the Registry is chock-full of keys whose values can't be edited anywhere else. Windows 2000 is pretty good about exposing formerly hidden features as settings in various GPOs, but since many Windows 2000 components are thinly disguised reissues of Windows NT 4.0 pieces and parts, hidden settings live on. In addition, some settings (such as the setting that controls whether Caller ID is used to identify incoming remote access calls) are available only by editing the Registry directly.

Keys you should leave alone altogether

Just because you can edit a key in the Registry doesn't mean you should. Many of Windows 2000's subsystems, particularly device drivers, are intended to be self-tuning; they continually adjust their settings based on the system's workload. If you directly adjust a setting behind its owner's back, your reward can be anything from reduced performance to an unbootable machine.