If your employees are not properly trained to maintain your systems, you risk compromising the reliability and availability that you should be achieving. Two programs can help you meet this goal: The Microsoft Readiness Framework and the Microsoft Certification Program.
Microsoft Readiness Framework
The Microsoft Readiness Framework (MRF) helps IT organizations develop individual and organizational readiness to use Microsoft’s products and technologies. This guidance includes assessment and readiness planning tools, learning roadmaps, readiness-related white papers, self-paced training, courses, certification exams, and readiness events.
MRF offers a structured approach to reliably and efficiently assess the technical requirements (both individual and organizational) necessary to plan, build, and manage solutions. The framework provides capability planning, organizational competency identification, and individual and organizational assessments.
For more information about how MRF fits in with the Enterprise Services Framework, see the Enterprise Services home page at http://www.microsoft.com/msf.
Microsoft Certification
Competitive organizations are led at all levels by professionals who know technology and can innovate, take initiative, and think strategically. Microsoft certification can help organizations find these technical leaders.
Microsoft certification is an objective way for businesses to identify individuals who have the technical abilities to help them compete in their industry and move forward with the most advanced Microsoft technology. Certification provides professionals with a credential that acknowledges their skills with Microsoft products.
For more information about Microsoft certification and other training opportunities, see the Microsoft Certification Web site at http://www.microsoft.com/trainingandservices/default.asp.
For information about learning services for Windows 2000 including online courses, seminars, and courseware about specific technologies, see the Windows 2000 Learning Center at http://www.microsoft.com/trainingandservices/default.asp?PageId=training&LearnCenterHtm=win2000.
Conclusion
The Windows 2000 Server product line is the most reliable set of server operating systems Microsoft has ever produced. The reliability improvements in Windows 2000 mean fewer network interruptions for end users, higher server uptime, and better availability.
Advanced Server meets the needs of essential business and e-commerce applications that handle heavier workloads and high-priority processes. You can readily increase your server capacity to keep pace with business growth while enhancing the availability of your important systems.
Windows 2000 Datacenter Server uses stringent standards for hardware and software configurations to deliver an OS designed to meet the highest demands for reliability and availability. It includes all the features in Advanced Sever plus greater clustering, load balancing, memory support, process controls, and other features optimized to deliver the high availability and reliability required for enterprise and larger departmental solutions.
This dependability is further enhanced by the Windows Datacenter Program, which gives customers an integrated hardware, software, and service offering—all delivered by Microsoft and qualified server vendors (OEMs).
A reliable system starts with hardware and software. To obtain maximum reliability and availability, you need to address people and process issues as well. Properly trained IT staff following best practices and using the expertise provided from external support programs will help ensure your systems are up and running. To help your staff gain the skills and support they need, Microsoft and third-party vendors offer a range of educational and support programs that complement the reliability capabilities offered by the Windows 2000 Server Family.
Appendix A: Reduced Reboot Scenarios
One of the major improvements with Windows 2000 is a reduction in the number of maintenance activities that require a reboot to complete. The following tasks no longer require rebooting your system.
File system maintenance
Extending an NTFS volume.
Mirroring an NTFS volume.
Hardware installation and maintenance
Docking or undocking a laptop computer.
Enabling or disabling network adapters.
Installing or removing Personal Computer Memory Card International Association (PCMCIA) devices.
Installing or removing Plug and Play disks and tape storage.
Installing or removing Plug and Play modems.
Installing or removing Plug and Play network interface controllers.
Installing or removing the Internet Locator Service.
Installing or removing Universal Serial Bus (USB) devices, including mouse devices, joysticks, keyboards, video capture, and speakers.
Networking and communications
Adding or removing network protocols, including TCP/IP, IPX/SPX, NetBEUI, DLC, and AppleTalk.
Adding or removing network services, such as SNMP, WINS, DHCP, and RAS.
Adding Point-to-Point Tunneling Protocol (PPTP) ports.
Changing IP settings, including default gateway, subnet mask, DNS server address, and WINS server address.
Changing the Asynchronous Transfer Mode (ATM) address of the ATMARP server. (ATMARP was third-party software on Windows NT 4.)
Changing the IP address if there is more than one network interface controller.
Changing the IPX frame type.
Changing the protocol binding order.
Changing the server name for AppleTalk workstations.
Installing Dial-Up Server on a system with Dial-Up Client installed and RAS already running.
Loading and using TAPI providers.
Resolving IP address conflicts.
Switching between static and DHCP IP address selections.
Switching MacClient network adapters and viewing shared volumes.
Adding a new PageFile.
Increasing the PageFile initial size.
Increasing the PageFile maximum size.
Software installation
Installing a device driver kit (DDK).
Installing a software development kit (SDK).
Installing Internet Information Service.
Installing Microsoft Connection Manager.
Installing Microsoft Exchange 5.5.
Installing Microsoft SQL Server 7.0.
Installing or removing File and Print Services for NetWare.
Installing or removing Gateway Services for NetWare.
Performance tuning
Changing performance optimization between applications and background services.
Appendix B: Tools for Third Parties
Making sure that software code doesn’t have errors can be difficult, particularly if that code runs inside the operating system kernel, such as device drivers. In the past, faulty device drivers have been a source of system unreliability. This Appendix describes typical coding errors that can hamper reliability, and how new tools and features in Windows 2000 help developers avoid or discover these errors. It concludes with a discussion of driver testing and certification.
Kernel-Mode Code Development
Software can be categorized into two major types of code: user-mode code, which includes application software such as a spreadsheet program; and kernel-mode code, such as core operating system services and device drivers. Development tools that help programmers write reliable application code aren’t necessarily appropriate for developers writing kernel-mode code. Because writing kernel-mode code presents special challenges, Windows 2000 Server includes tools for kernel-mode developers.
Device drivers, often simply referred to as drivers, are the kernel-mode code that connects the operating system to hardware, such as video cards and keyboards. To maximize system performance, kernel-mode code doesn’t have the memory protection mechanisms used for application code. Instead, this code is trusted by the operating system to be free of errors. In order to safely interact with other drivers and operating system components, drivers and other kernel-mode code must follow complex rules. A slight deviation from these rules can result in errant code that can inadvertently corrupt memory allocated to other kernel-mode components.
Some kernel-mode code errors show up immediately during testing. But other types of errors can take a long time to cause a crash, making it difficult to determine where the problem originates. In addition, it is not easy for driver developers to fully test kernel-mode code because it is difficult to simulate all the workload, hardware, and software variables that might be encountered in a production environment.
To address these issues, Windows 2000 Server includes the following features and tools to help developers produce better drivers:
Pool Tagging
Driver Verifier
Device Path Exerciser
Pool Tagging
The Windows NT 4.0 kernel contains a fully shared pool of memory that is allocated to tasks and returned to the pool when no longer needed. Although using the shared memory pool is an efficient way of using memory in a run-time system, the shared pool can create problems for driver developers if they make a mistake in their code.
One common error is to let a kernel-mode component write outside of its memory allocation. This action can corrupt the memory of another kernel-mode component and cause a system failure.
Another common mistake is to allocate memory for a driver process and then fail to release it when the process is finished, creating a memory leak. Memory leaks slowly consume more and more memory and eventually exhaust the shared memory pool, which causes the system to fail. This scenario may take a long time to develop. For example, a driver that requests a small amount of memory and only forgets to release that memory in rare situations will take a long time to exhaust the memory pool.
Both types of errors can be hard to track down. To help developers find and fix such memory problems, Pool Tagging (also known as the Special Pool), has been added to Windows 2000. For testing purposes, Pool Tagging lets kernel-mode device driver developers make all memory allocations to selected device drivers out of a special pool, rather than a shared system pool. The end of the special pool is marked by a Guard Page. If an application tries to write beyond the boundary of their memory allocation, it hits a Guard Page, which causes a system failure. Once alerted by the system failure, a developer can track down the cause of the memory allocation problem.
To help developers find memory leaks, Pool Tagging also lets developers put an extra tag on all allocations made from the shared pool to track tasks that make changes to memory.
Driver Verifier
The Driver Verifier is a series of checks added to the Windows 2000 kernel to help expose errors in kernel-mode drivers. The Driver Verifier is ideal for testing new drivers and configurations for later replication in production. These checks are also useful for support purposes, such as when a particular driver is suspected as the cause of crashes in production hardware. The Driver Verifier also includes a graphical user interface tool for managing the Driver Verifier settings.
The Driver Verifier tests for specific sets of error conditions. Once an error condition is found, it is added to the existing suite of tests for future testing purposes. The Driver Verifier can test for the following types of problems:
Memory corruption. The Driver Verifier checks extensively for common sources of memory corruption, including using un-initialized variables, double releases of spinlocks, and pool corruption.
Writing to pageable data. This test looks for drivers that access pageable resources at an inappropriate time. The problems that result from these types of errors can result in a fatal system error, but may only appear when a system is handling a full production workload.
Handling memory allocation errors. A common programming error is neglecting to include adequate code in the driver to handle a situation when the kernel cannot allocate the memory the driver requests. The Driver Verifier can be configured to inject random memory allocation failures to the specified driver, which allows developers to quickly determine how their drivers will react in this type of adverse situation.
Because Driver Verifier impacts performance, it shouldn’t be used continuously, or in a production environment. Developer guidelines for using Driver Verifier are published at http://www.microsoft.com/hwdev/driver/driververify.htm.
Device Path Exerciser
The Device Path Exerciser tests how a device driver handles errors in code that use the device. It does this by calling the driver, synchronously or asynchronously, through various user-mode I/O interfaces and testing to see how the driver handles mismatched requests. For example, it might connect to a network driver and ask it to rewind a tape. It might connect to a printer driver and ask it to re-synchronize the communication line. Or, it might request a device function with missing, small, or corrupted buffers. Such tests help developers make their drivers more robust under error conditions, and improve drivers that cannot handle the tested calls properly.
Devctl, the Device Path Exerciser, ships in the Hardware Compatibility Test 8.0 test suite, available at http://www.microsoft.com/hwtest/TestKits/.
Driver Signing
In addition to the tools provided for driver developers, Microsoft has also added a way to inform users if the Microsoft testing process has certified the drivers they are installing.
Windows 2000 includes a new feature called Driver Signing. Driver Signing is included in Windows to help promote driver quality by allowing Windows 2000 to notify users whether or not a driver they are installing has passed the Microsoft certification process. Driver Signing attaches an encrypted digital signature to a code file that has passed the Windows Hardware Quality Labs (WHQL) tests.
Microsoft will digitally sign drivers as part of WHQL testing if the driver runs on Windows 98 and Windows 2000 operating systems. The digital signature will be associated with individual driver packages and will be recognized by Windows 2000. This certification proves to users that the drivers they employ are identical to those Microsoft has tested, and notifies users if a driver file has been changed after the driver was put on the Hardware Compatibility List.
If a driver being installed has not been digitally signed, there are three possible responses:
Warn: lets the user know if a driver that’s being installed hasn’t been signed and gives the user a chance to say “no” to the install. Warn will also give the user the option to install unsigned versions of a protected driver file.
Block: prevents all unsigned drivers from being installed.
Ignore: allows all files to be installed, whether they’ve been signed or not.
Windows 2000 will ship with the Warn mode set as the default.
Vendors wishing to have drivers tested and signed can find information on driver signing at http://www.microsoft.com/hwtest/. Only signed drivers are published on the Windows Update Web site at http://windowsupdate.microsoft.com/default.htm.
Developing and debugging user-mode code
User mode is the portion of the operating system in which application software runs. Windows 2000 includes a new tool, PageHeap, which can help developers find memory access errors when they are working on non-kernel-mode software code.
Heap refers to the memory used to temporarily store code. Heap corruption is a common problem in application development. Heap corruption typically occurs when an application allocates a block of heap memory of a given size and then writes to memory addresses beyond the requested size of the heap block. Another common cause of heap corruption is writing to a block of memory that has already been freed. In both cases, the result can be that two applications try to use the same area of memory, leading to a system failure. To help developers find coding errors in memory buffer use faster and more reliably, the PageHeap feature has been built into the Windows 2000 heap manager.
When the PageHeap feature is enabled for an application, all heap allocations in that application are placed in memory so that the end of the heap allocation is aligned with the end of a virtual page of memory. This arrangement is similar to the tagged pool described for kernel memory. Any memory reads or writes beyond the end of the heap allocation will cause an immediate access violation in the application, which can then be caught within a debugger to show the developer the exact line of code that is causing heap corruption.
Appendix C: Windows 2000 OS and Memory Protection
At the center of the reliability and availability improvements in Windows 2000 are new protections for the operating system and memory. Many of the problems that cause instability can be traced to unwanted affects on the core of the operating system, the kernel, where essential system services are performed. Because it controls the entire operating system, code errors that affect the kernel have a major impact on reliability. Errors that affect memory are also a common source of instability.
Windows 2000 improves reliability by providing early detection and prevention of improper memory management practices in applications, kernel components, and device drivers. The operating system is designed to gracefully manage application and system errors and exceptions, without bringing down the server. In addition, to ensure that one program’s fault will not affect the operating system or other programs, protected subsystems isolate programs in unique memory locations.
T
o make it easier to visualize the specific improvements in Windows 2000 that address instability issues, this appendix provides an overview of the operating system architecture and memory management.
Figure 1: The Windows 2000 Server Architecture is made up of user-mode and kernel-mode components. User mode is the portion of the operating system in which application software runs. Kernel mode is the portion that interacts with computer hardware. Many of the operating system reliability improvements add protection for the kernel-mode processes.
The Windows 2000 operating system provides the environment in which applications run. To do this, it contains a collection of small, self-contained software components that work together to perform tasks. Each component provides a set of functions that act as an interface to the rest of the system. This collection of modules provides the means to access processor and all other hardware resources. The operating system also provides a mechanism by which applications and components may communicate with one another.
Kernel Mode vs. User Mode
Windows 2000 divides the executing code into the following two areas or modes.
User Mode
Software in user mode operates in a non-privileged state with limited access to system resources. For example, this software can’t directly access hardware. Windows 2000-based applications and protected subsystems run in user mode. The protected subsystems run in their own protected space and do not interfere with each other. They are divided into the following two groups:
Environment subsystems (see upper-right area of Figure 1 above) are services that provide application programming interfaces (APIs) specific to an operating system. Using the environment subsystems, Windows 2000 is able to run applications written for different operating systems, such as OS/2, using these APIs.
Integral subsystems are services that provide interfaces with important operating system functions such as security and network services. The four boxes in the upper-left area of Figure 1 above represent the integral subsystems.
Kernel Mode
In kernel mode, software can access all the system resources such as computer hardware and sensitive system data. The kernel-mode software constitutes the core of the operating system and can be grouped as follows:
Executive contains system components that are responsible for providing system services to environment subsystems and other executive components. They perform system tasks such as input/output (I/O), file management, virtual memory management, resource management, and interprocess communications.
Device drivers translate calls from components, such as a request to print, into hardware manipulation.
Hardware abstraction layer (HAL) isolates the rest of the Windows 2000 Executive from the specific hardware, making the operating system compatible with multiple processor platforms.
Microkernel manages the microprocessor. It performs crucial functions such as scheduling, interrupt, exception dispatching, and multiprocessor synchronization.
Memory Model
Windows 2000 adds features to address some of the potential challenges that arise as different processes share memory. To understand these improvements, it helps to understand the basics of how Windows 2000 manages memory.
W
indows 2000 uses a Virtual Memory Manager (VMM) to manage the use of virtual and physical memory. (Shown as the Memory Manager in Figure 1, above.)
Figure 2:To allow a number of applications to share a finite amount of RAM, the Virtual Memory Manager swaps pages of memory between virtual memory and hard disk space.
Virtual memory refers to how the operating system makes memory available to applications. Windows 2000 supports 4 gigabytes (GB) of virtual memory. The upper 2 GB is reserved for kernel-mode processes and the lower 2 GB is shared by kernel-mode and user-mode processes.
Physical memory refers to the RAM chips installed in the computer. VMM uses a memory-mapping table to keep track of the virtual addresses that belong to each process and where the actual data referenced by these addresses resides in physical memory. To let a number of applications share memory so they can run at once, the VMM uses a process called paging to swap memory contents between RAM and disk storage. The contents being swapped are called pagefiles.
For More Information
For the latest information on Windows 2000, check out our Web site at http://www.microsoft.com/windows2000 and the Windows 2000/NT Forum at http://computingcentral.msn.com/topics/windowsnt.
See also:
Windows 2000 Server and Advanced Server home page: http://www.microsoft.com/windows2000/server
Windows 2000 Datacenter Server home page: http://www.microsoft.com/windows2000/datacenter
Microsoft Application Center 2000 home page: http://www.microsoft.com/applicationcenter/
Introduction to reliability and availability in Windows 2000 Server: http://www.microsoft.com/windows2000/guide/server/overview/reliable/default.asp
Microsoft Press Windows 2000 resources: http://mspress.microsoft.com/Windows2000
Microsoft Support options page: http://support.microsoft.com/directory/overview.asp.
Microsoft Certified Support Centers home page: http://www.microsoft.com/support/mcsc/
Microsoft Enterprise Services home page:
http://www.microsoft.com/msf
Microsoft Operations Framework white papers: http://www.microsoft.com/trainingandservices/MOFoverview
Microsoft Certification home page: http://www.microsoft.com/trainingandservices/default.asp
Hardware Design Guide Version 2.0 for Microsoft Windows NT Server: http://msdn.microsoft.com/library/books/serverdg/hardwaredesignguideversion20formicrosoftwindowsntserver.htm
Server Design FAQ: http://www.microsoft.com/HWDEV/xpapers/SDG2FAQ/FAQ1.htm
Microsoft Windows Hardware Quality Labs home page: http://www.microsoft.com/hwtest/default.asp
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