Classes of Servers - A reference for Designing Servers and Peripherals for the Microsoft® Windows nt® Server Operating...

Servers perform a huge variety of tasks and combinations of tasks, resulting in many configurations. To specify requirements in a meaningful way, this guide first defines a basic set of requirements for a generic (or basic) server platform. This guide then provides additional recommendations and requirements for two more server usage models, as described here:
Basic server. As with all the platforms in this guideline, this server can be used in any and all environments. This server is described by a set of requirements and recommendations that seek to define a well-rounded, general-purpose server platform used solely as a server. Such a server might be used in small businesses or for a variety of uses in larger businesses ranging from departmental use to clustered applications in the enterprise. Administration can be local or remote.
This server provides excellent baseline performance characteristics for general-purpose, server-based computing. Its baseline capabilities include high availability, serviceability, scalability, ease of use, and ease of administration. This platform and its requirements are used as a basis for other types of servers defined by this guideline.
Small office/home office (SOHO) server. Although it can be used in any environment, this server platform has features that increase its ease of use and deployment in small businesses that generally do not have great experience in use and deployment of server systems. This general-purpose platform handles file, print, and client-server application requirements. This server must have a broad set of attributes to handle all typical server tasks in a limited environment. Quick recovery is required, because down time will immediately impact the small office’s ability to conduct business.
The system must be easy to set up and must be easily manageable from a remote location such as the headquarters for a value-added retailer (VAR) or directly by the server owner, who might have little or no computer knowledge. To increase ease of use and availability, the system should be capable of exploiting the reliability features of Windows NT, such as disk mirroring and clustering. The system should have low entry costs and low recurring costs, as it is frequently deployed where cost is a driving issue.
Also, this type of server has additional requirements driven by the usage and deployment model for this platform. Frequently, this class of server will be deployed in environments where it might fulfill the role of a client workstation for a user in addition to its usual work of performing server tasks. Among other things, this dual use imposes additional requirements for power management and configuration to enable behavior compatible with this environment.
Enterprise server. This server, as with the other two types described previously, can be used in any environment but is frequently deployed as the building block for a large organization, where it often performs special-purpose tasks such as handling and routing e‑mail or storing financial data. Because this server is an indispensable part of the organization, it must be highly available. Therefore, software and hardware mechanisms must be in place to eliminate unplanned down time.
Preparing for ACPI and OnNow Design
Windows NT Server 5.0 will include support for ACPI, which supports operating system–based power management and Plug and Play system–configuration capabilities. This guide introduces some of the system and device capabilities required for hardware that is Plug and Play-compliant when used with Windows NT 5.0.
The goal of the OnNow design initiative is to ensure that all system components work together to enable robust and reliable system configuration and power management. The operating system and applications work together intelligently to deliver effective power management. All devices connected to the system or added by the user participate in the device power management scheme.
The OnNow design initiative means new requirements for the operating system, applications, device drivers, and hardware in order to deliver transparent power management and improved integration of components. The changes include:
Enhanced core operating system functionality for power management.
Win32 Driver Model (WDM), which supports power management and Plug and Play and provides a common set of I/O services and binary-compatible device drivers among Windows® 98 and Windows NT for targeted device classes (audio, input, video, and still imaging) and bus classes (USB and IEEE 1394).
A new system interface for operating system–directed power management and Plug and Play. The ACPI design also provides future extensibility and improved system integration.
Device and bus hardware power management interfaces and state definitions.
An application architecture that allows applications to integrate into power management of the system.
The ACPI specification defines a flexible and abstract hardware interface that enables a wide variety of server systems to implement power and thermal management functions while meeting the cost and feature requirements of the target market. ACPI also provides device configuration and generic system-event mechanisms for Plug and Play, unifying the power management interface with the Plug and Play interface.
The ACPI implementation is independent of the processor architecture and enables the operating system to direct power management throughout the system.
For more information about ACPI and the OnNow design initiative, see the OnNow web site at http://www.microsoft.com/hwdev/onnow.htm. Additional information about system configuration and power management for an ACPI system is available at http://www.microsoft.com/hwdev/desguid/onnowpc97.htm.
Processor Requirements
This section summarizes design issues related to processors used on systems that are compliant with the requirements in this guide.
Windows NT is designed to run on platforms that use Intel486 (with uniprocessor support only), Intel Pentium, Intel Pentium with MMX technology, Pentium Pro, Pentium II, or compatible processors that use the Intel Architecture instruction set. When Windows NT is running on an Intel Architecture processor, a virtual‑86 processor mode allows direct execution of most instructions in MS‑DOS® – based applications. In virtual‑x86 mode, a few instructions, such as I/O, must be emulated to virtualize the hardware.
Windows NT can also run on RISC-based computers, which includes computers with Digital Alpha processors. When Windows NT is running on a RISC-based processor, hardware support is not available for executing such MS‑DOS instructions, so Windows NT emulates all these instructions and provides a virtual hardware environment using the Virtual Device Manager (VDM). The Windows NT VDM also supports ROM BIOS interrupt services, MS‑DOS Interrupt 21 services, and virtual hardware for devices using virtual device drivers.
Advanced RISC computing (ARC) refers to a RISC-based computer architecture standard associated with the Advanced Computing Environment (ACE) consortium. For ACE-compliant platforms, the system firmware must support bootstrap loading and execution as an abstracted set of ARC routines and ARC devices.
For both kinds of platforms, a hardware abstraction layer (HAL) interfaces between the hardware and the system. Device drivers for certain types of devices create an alias between the names of their device objects and the corresponding ARC device name by calling the appropriate application programming interface (API).
For some devices in Windows NT, there are no differences in the requirements for supporting any microprocessor platform. For example, a network adapter driver calls DMA-related functions of the NDIS interface library for DMA operations between the host and the network adapter. These functions support maximized portability so the driver can run on both Intel Architecture and RISC‑based systems.
However, some differences in microprocessor platform requirements must be addressed in the Windows NT device driver. For example:
Phase 1 of Windows NT system startup is microprocessor-platform–specific. On Intel Architecture servers, the hardware boot ROM loads a boot sector, which in turn loads the NTLDR. For most RISC-based platforms, the firmware loads necessary ARC drivers, acquires hardware configuration data, and then loads the OSLOADER.
Phase 2 of Windows NT system startup sets up memory, captures hardware configuration data, constructs a description of the hardware in memory, and puts a pointer to this description into the loader block.
On Intel Architecture servers running Windows NT, there are two kinds of video miniport drivers: video graphics array–compatible (VGA-compatible) miniports and miniports that rely on having the system-supplied VGA miniport driver or other VGA-compatible Super VGA (SVGA) miniport driver loaded concurrently.
On RISC-based servers, miniport drivers rely on the system-supplied VGA support, if necessary. For all RISC-based servers running Windows NT, video miniport drivers need not supply any special support for full-screen MS‑DOS–based applications. Instead, video miniport drivers must be set up to configure themselves in the registry.
Part 1
Basic Server Requirements
This part provides a collection of the generic requirements for servers.
Chapter 2 Basic System Component Requirements 11
Basic Component Requirements 12
System Microprocessor Requirements 13
Memory Requirements 14
Configuration and Power Management Requirements 15
Chapter 3 Basic Bus and Device Requirements 25
PCI Bus Requirements 25
USB Requirements 32
Other Bus Requirements 34
Device Requirements 36
Chapter 4 Basic Networking and Communications Requirements 43
Network Adapter Requirements 45
Modem Requirements 49
Requirements for Other Communications Devices 53
Chapter 5 Basic Storage Device Requirements 63
SCSI Controllers and Peripherals 65
IDE Controllers and Peripherals 68
Fibre Channel Controllers and Peripherals 72
Erasable Disk Drives 72
CD-ROM and Other CD Drives 73
Tape Drives 79
Media Changers 81
Chapter 6 Basic Physical Design and Hardware Security Requirements 83
Physical Design Requirements 83
Hardware Security Requirements 85
Chapter 7 Basic Reliability, Availability, and Serviceability Requirements 87
Backup and Reliability Requirements 87
High Availability Requirements 90
Manageability Baseline Requirements 91
Chapter 2
Basic System Component Requirements
This chapter presents the basic system requirements for design of commodity servers that run the Microsoft Windows NT Server operating system, including the basic design issues for computer systems based on Intel Architecture and RISC-based processor platforms.
Tips for selecting high-performance system components. For manufacturers who want to select high-performance components for server systems, the following are design features to look for when selecting components that will improve memory performance:
Implement PCI controllers as peer bridges to improve I/O bandwidth.
Support fast, large, expandable memory.
Support the largest Level 2 (L2) cache possible for systems with Pentium or compatible processors.
Note: The system requirements defined in this publication provide guidelines for designing servers and peripherals that deliver an enhanced user experience when implemented with Windows NT Server. These requirements are not the basic system requirements for running the Windows NT Server operating system.
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