Ask the Windows 2000 Dev Team

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Every other week we put your How-Come-You-Did-That questions to the Windows 2000 development team. Submit your questions here.

Codebase for Windows 2000, Reliability, Availability

Q: Is Windows 2000 the next version of Windows 98 or Windows NT? My boss wants us to switch to Windows NT Workstation, and I am considering using Windows 2000.

A: In terms of code base, Windows 2000 is the next version of Windows NT. You will find the same robustness and security features you have come to expect in prior versions of Windows NT. We have also included the Plug and Play functionality that you appreciate in the Windows 9x products, which makes Windows 2000 a compelling product for business desktops and laptops.

For more information on the different editions of Windows 2000, please visit the Windows 2000 Product Guide. The Windows 2000 team has made it possible to upgrade from both Windows 98 and Windows NT 4.0. You can easily install the corresponding Windows 2000 version over either operating system.

Q: So what does Microsoft mean by "reliability" and "availability"? I run a corporate enterprise and I want to know if we're talking about the same thing.

A: We define reliability as the probability that a system is in an operational state for a given interval of time. Highly reliable systems are characterized by infrequent service interruptions. Related to reliability is availability, defined as the probability that a given system is in an operational state at a given time. Availability can be thought of as the probability that a given server or service is available when it is requested to perform its function.

Early in the development cycle for Windows 2000, Microsoft worked with a large body of data — collected internally and from customers running mission-critical operations — to analyze the causes of Windows NT 4.0 failures. This data helped us enhance the stability and reliability of Windows 2000, and it helped us develop tools that can help administrators analyze and recover from failures.

Q: What kind of changes did you make to Windows 2000 to make it reliable?

A: We made changes to the kernel-mode that include:

  • Kernel-mode write protection, which provides write protection for code and read-only subsections of the kernel and device drivers, just as it always has for user-mode programs and dynamic-link libraries (.dll files).

  • Code signing uses existing Digital Signature cryptographic technology to verify the source of a system file before it is installed.

  • Pool tagging lets kernel-mode device-driver writers produce better drivers and cleaner code by making all memory allocations to selected device drivers out of a special pool, rather than a shared system pool.

We also added new features, including:

  • Safe-mode boot, which uses minimal services to boot the machine so that users can correct installation problems or change settings that have caused boot problems.

  • Recovery console that can be run from the Windows 2000 CD in text mode to reduce reliance on boot floppies or repair disks.

  • Faster CHKDSK to lessen recovery time.

  • Kernel-only crash dumps, which optionally writes only the contents of the kernel to disk after a crash.

  • Kill process tree to ensure that all processes spawned by a parent process are removed when the parent process is stopped.

  • Internet Information Server (IIS) Automatic Application Restart which gives an administrator a one-step process to reliably restart IIS.