I2O Intelligent I/O Devices
Although Intelligent Input/Output (I20) will not have a big impact on server performance in 1998, it is nonetheless an important technology. In theory, I20 devices can turn your computer from a master talking to slave I/O cards into a collective of intelligent devices that cooperate to get work done.
Figure 2 shows the data transfer path from a disk drive to a network controller. The system must read the data into system memory from the I/O subsystem, process the data, and then write it back to the network interface. I20, however, will let the system transfer data directly from the disk subsystem to the network, as Figure 3 shows. Because the data travels directly from the disk controller to the network controller, the only additional traffic is messages passing between the OS and the controllers to direct the data.
Because I2O requires new motherboards, adapters, and modifications to the OS, predicting when it might become a common solution is impossible. However, Microsoft is adding support for I2O to NT 5.0, and the computer industry might get an early look at that support if Microsoft offers I20 as a service pack for NT 4.0. For more information about I20, check out Intel's Web page (http://www.intel.com/procs/servers/i2otech/index.htm).
Universal Serial Bus
One technology that will appear in the Intel server platform this year is the Universal Serial Bus (USB). USB supplements the serial ports today's systems use and provides a common interface for a variety of low-bandwidth devices such as modems, keyboards, mouse devices, and scanners. The immediate utility of USB on servers is hard to see, because few devices that typically attach to servers are available with a USB interface. However, this situation is likely to change.
There is some question whether USB on a server is a good idea, particularly in secure environments. One of the key features of USB is that it accepts hot-plug devices so that the system recognizes the device without user intervention. In many secure environments, servers run without a keyboard, and the ability to plug in a keyboard in such a secure situation is not desirable.
Advanced Configuration and Power Interface
ACPI is a standard Microsoft, Intel, and several other vendors developed to improve Intel-based hardware platforms' ease of use and management. NT 5.0 requires ACPI to fully implement advanced power-management features such as Wake-on LAN, in which a server can be in sleep mode until a network packet wakes it up. In the past, Intel-based systems implemented power management that was fairly inflexible in the BIOS. ACPI will let the OS completely control how much power goes to which devices. Full implementation of ACPI is useful for desktops; however, its application in servers is crucial. Without an ACPI-compliant system, you won't get the benefits of hot-plug PCI.
Although Microsoft touts ACPI as an important component of NT 5.0, the current crop of 4-way Intel servers will never fully support ACPI because of hardware limitations. These limitations don't mean that NT 5.0 won't run on non-ACPI compliant hardware, only that the hardware won't implement all ACPI features. If you want to know more about ACPI, you can find the full ACPI specifications at http://www.teleport.com/~acpi/spec.htm.
New Features in NT Server 5.0
Improvements in the Intel server platform are only part of the coming changes to the business-server development equation. Other and equally significant parts of the equation are changes in software: Microsoft has big plans for NT Server 5.0. The primary purpose of NT 5.0 is to lower total cost of ownership (TCO) and improve scalability, security, and administration. NT 5.0 will accomplish these goals with a variety of features, including Plug and Play (PnP), IntelliMirror, media management services, Active Directory (AD), and Microsoft Management Console (MMC). You can read about the new features in NT 5.0 and find links to additional information at http://www.microsoft.com/ntserver/basics/future/windowsnt5/features.asp. To learn how you can get your enterprise ready for NT 5.0 today, see Sean Daily, "10 Steps to Prepare for NT 5.0 Now," February 1998.
PnP. Today, PCI in NT is a largely static implementation. If you change a device, you have to reboot the system and perhaps reload drivers. This requirement applies even to systems with hot-pluggable PCI slots. NT 5.0 will be the first release of NT that fully uses the PnP capabilities of the PCI bus. For most implementations, this capability means simpler installation of new devices. In addition, for servers with hot-plug PCI and redundant network or disk interfaces such as fibre channel, this capability will enable a higher level of fault tolerance. With NT 4.0, if your disk controller fails, the system will go down even if it is protected by RAID. However, if you have a pair of fibre channel controllers attached to a dual-ported drive and your disk controller fails, your system can stay up while you replace the failed controller.
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