HP ProLiant 1200 Eliminating Single Points of Failure and Enabling Rapid Recov - Page 5

ECG0094/1197 Eliminating Single Points of Failure (cont.) ... A Pentium processor requires tightly controlled power from a dedicated power supply. If a power supply module supporting a processor fails, the system goes down. To prevent that, Compaq servers have three processor power supply modules to support every two processors (two active and one redundant) or, in some models, fully redundant power modules. If one power module fails, the redundant power module takes over operation without interrupting system operation. To minimize the impact of a software, memory, or processor failure, Compaq implements rapid recovery tools in the system management hardware, software, and firmware that are included on all Compaq servers. Two of these tools, Automatic Server Recovery-2 (ASR-2) and Server Health Logs, work together to restore a server to its original state. If an error occurs in a subsystem, ASR-2 will log the error in the Server Health Logs, attempt to restart the system, and take other necessary action to avoid subsequent faults, as specified by the system administrator. For example, if a processor becomes inoperable or fails the power-up self-test, power to that processor is disconnected and the boot process continues. The other processors continue to run, and an alert message is sent to the system administrator. Replacement of the failed processor can be scheduled to minimize downtime. I/O Expansion A number of developments are improving the availability of expansion cards. With the implementation of redundancy and, in some areas, hot plug capability, Compaq servers continue to move closer to the goal of maximum system reliability. Compaq leads the industry in developing and delivering PCI Hot Plug technology. Compaq's PCI Hot Plug Adapter technology allows hot replacement, which is the replacement of one PCI adapter with an identical adapter while the system is operating. This technology also includes hot upgrade (replacement of a PCI adapter with an upgraded adapter) and hot expansion (addition of a PCI adapter to an empty slot). A standard implementation (compliant with PCI SIG guidelines), Compaq's PCI Hot Plug Adapter technology is backward compatible. A PCI Hot Plug Adapter can be installed without using its hot plug functionality until such time as all the requirements (PCI Hot Plug Adapter, a hot plug aware operating system, a user interface, and hot plug device driver support) are in place. This allows a mix of the existing components and the new hot plug technology to be in use at the same time, protecting the substantial investment companies make in network and storage hardware, and allowing a gradual move toward improved system availability in a cost-effective manner. Intel has licensed the Compaq PCI Hot Plug Controller for use on its system board products. All industry-standard PCI adapters can be used in Compaq's hot plug environment without modification. However, device drivers require new features to enable use of Compaq servers' hot plug capabilities. Leading independent hardware suppliers committed to modifying their device drivers to be hot plug aware include Adaptec, Dialogic, Digi International, Mylex, Standard Microsystems Corporation, and SysKonnect. In addition, Compaq is delivering hot plug capable drivers for its own leading PCI server adapters. Support for PCI Hot Plug technology is being built into current and upcoming versions of Windows NT 5.0, Novell IntranetWare, and SCO UNIX operating systems. For more information about PCI Hot Plug, see technology briefs 398A/1196, PCI Hot Plug Technology; ECG004.0897, PCI Hot Plug Technology with SCO Software Architecture; 064A/0797, Deploying PCI Hot Plug in a Microsoft Windows NT Environment, and 131A/0397, PCI Hot Plug Technology with Novell Architecture.