Electrical computers and digital data processing systems: input/ – Intrasystem connection – Bus expansion or extension
Reexamination Certificate
1999-04-30
2002-11-26
Auve, Glenn A. (Department: 2181)
Electrical computers and digital data processing systems: input/
Intrasystem connection
Bus expansion or extension
C714S006130, C714S042000
Reexamination Certificate
active
06487623
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a computer system having hot-pluggable components such as memory modules, and more particularly, to replacing, upgrading and/or adding the hot-pluggable memory modules without disturbing operation of the computer system.
2. Description of the Related Technology
Use of computers, especially personal computers, in business and at home is becoming more and more pervasive because the computer has become an integral tool of most information workers who work in the fields of accounting, law, engineering, insurance, services, sales and the like. Rapid technological improvements in the field of computers have opened up many new applications heretofore unavailable or too expensive for the use of older technology mainframe computers. These personal computers may be used as stand-alone workstations (high end individual personal computers) or linked together in a network by a “network server” which is also a personal computer which may have a few additional features specific to its purpose in the network. The network server may be used to store massive amounts of data, and may facilitate interaction of the individual workstations connected to the network for electronic mail (“e-mail”), document databases, video teleconferencing, whiteboarding, integrated enterprise calendar, virtual engineering design and the like. Multiple network servers may also be interconnected by local area networks (“LAN”) and wide area networks (“WAN”).
A significant part of the ever increasing popularity of the personal computer, besides its low cost relative to just a few years ago, is its ability to run sophisticated programs and perform many useful and new tasks. The personal computer thus has become an indispensable part of business and the economy. The network server plays an even more critical part in business computing by tying together the personal computer workstations into a network (LAN and WAN), and for storing and/or forwarding critical business information. This business information may comprise for example: databases, word processing, spreadsheets, drawings, graphics, e-mail, graphics, pictures, and the like. Therefore, it is imperative that there be a high availability of the computer system.
Replacement of defective components in a computer system or expanding the capabilities thereof, typically requires shutting down the computer needing service. If a defective component or upgrade is required in a network server, the potential for rendering inoperative all of the personal computers depending on that server is very high. The necessity for high availability of server operation has created hot-pluggable component designs as more fully described in commonly owned U.S. patent application Ser. No. 08/940,419, filed Sep. 30, 1997, entitled “Installation and Removal of Components of a Computer” by Sompong P. Olarig, Kenneth A. Jansen and Paul A. Santeler, and is hereby incorporated by reference. Hot-pluggable component designs, however, have typically required specially designed hardware and software modifications to the operating system software for implementation thereof.
There are some components in a computer system that may become defective but still function for their intended purpose for a period of time. For example, system memory comprising a plurality of random access memory (RAM) devices may have added circuitry for error checking and correction (ECC) which allows memory storage bit errors to be corrected without the data stored therein being corrupted. ECC covers up memory storage bit errors, but it does not fix the RAM device(s) causing the problem. Ultimately, the defective RAM device(s) must be replaced before further degradation, which ECC cannot correct, causes the computer system to become inoperative. Upgrading and/or adding RAM devices without shutting down the computer system is also highly desirable.
What is needed is a system, method and apparatus for replacing failing but functional computer components, upgrading and/or adding components without disturbing the normal operation of the computer system, without requiring specially designed hot-pluggable components, and without installing special operating system software patches.
SUMMARY OF THE INVENTION
The present invention overcomes the above-identified problems as well as other shortcomings and deficiencies of existing technologies by providing in a computer system an apparatus, method and system for replacement of existing faulty components or expansion/addition of components without requiring the computer system to be brought off-line during operation thereof. Component replacement may be performed by logic and firmware within the computer system and requires no software operating system, application programming interface (API) or driver modifications. Industry standard components may be used with the present invention for the hot-pluggable capabilities.
An example of a replacement component is a random access memory (RAM) module that is plugged into a computer system memory connector. Other computer system components are contemplated herein and are within the scope of the invention. Some of these components may be, for example but not limitation: modem, network, video, SCSI, disk drive, and fibre channel interfaces; a processor in a multi-processor system, etc.
An embodiment of the present invention utilizes one or more RAM module connectors or memory connectors which may be electrically isolated from the computer system. Isolation, preferably, is obtained with field effect transistor (FET) signal isolation buffers interposed between the connector signal pins and a memory controller. Power FET switches are interposed between the connector power pins and the computer system power buses. Each isolatable memory connector may also contain one or more software and/or hardware controllable light emitting diodes (LEDs) of various colors (electronically controllable) to indicate the status of the corresponding memory connector. Control and sense logic is implemented to control the operation of the FET signal isolation buffers, power FET switches, LEDs, and memory bus operation between the system memory controller and the isolatable memory connectors. This control and sense logic may monitor (“snoop”) memory bus activity so that a memory connector may be brought on or off line only when the memory bus is inactive, i.e., no read or write activities.
When an undesirable number of correctable memory errors occur, the present invention enables on-line replacement of the faulty memory without disturbing the normal operation of the computer system. Correctable memory errors are the most prevalent errors encountered in a computer system having ECC memory. When a particular memory connector having faulty memory is detected, appropriate management traps and alerts are initiated through system software and/or hardware. An indicator LED associated with the faulty memory connector may be activated in such a way as to indicate the condition and location of that connector. In addition, another LED associated with a spare memory connector may indicate that the location of that spare connector has or is available for a replacement memory module. Due to the correctable nature of ECC memory, the faulty memory module will still continue to return correct data to the computer system. Upon inspection of the memory connectors and LEDs associated therewith, an operator or technician can see the status of each memory connector and may determine which connector has the faulty memory module and which memory connector has or can accept a new memory module to replace the faulty one.
The unused memory connector, as indicated by the associated LED, is completely isolated from the computer system memory by a set of FET isolation buffers and the computer system power buses by power FET switches. This unused memory connector either has or can accept insertion of a new memory module without affecting normal operation of the computer system. Upon need and detection of a new memory
Clohset Steve
Emerson Theodore F.
Michels Peter
Nguyen Vincent
Auve Glenn A.
Compaq Information Technologies Group L.P.
Conley & Rose & Tayon P.C.
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