System for storing display data during first time period prior to failure of computer and during second time period after reset of the computer

• US 5,852,720 A
• Filed: 08/16/1996
• Issued: 12/22/1998
• Est. Priority Date: 08/16/1996
• Status: Expired due to Term

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Compaq Computer Corporation (HP Inc.)
• Inventors: Gready, R. Scott, Clark, Gordon R., Ellinger, Wesley M.
• Primary Examiner(s): Meky, Moustafa M.
• Application Number:
  US08/695,828
• Time in Patent Office: 858 Days
• Field of Search: 395/821, 395/822, 395/823, 395/872, 395/200.33, 395/200.47, 395/200.49, 395/788, 395/114, 395/118, 395/182.02, 395/182.03, 395/184.01, 395/185.04, 345/516, 345/203, 345/508, 345/507, 345/186
• US Class Current: 709/217
• CPC Class Codes: G06F 11/0709 in a distributed system consisting of a plurality of standalone computer nodes, e.g. clusters, client-server systems
• CPC Class Codes: G06F 11/0766 Error or fault reporting or storing
• CPC Class Codes: G06F 11/2294 by remote test
• CPC Class Codes: G06F 11/327 Alarm or error message display
• CPC Class Codes: G06F 11/3414 Workload generation, e.g. scripts, playback
• CPC Class Codes: G06F 11/3466 Performance evaluation by tracing or monitoring
• CPC Class Codes: G06F 11/3476 Data logging G06F11/14, G06F11/2205 take precedence
• CPC Class Codes: G06F 11/3485 for I/O devices
• CPC Class Codes: G06F 2201/88 Monitoring involving counting
• CPC Class Codes: H04L 41/06 Management of faults, events, alarms or notifications
• CPC Class Codes: H04L 41/22 comprising specially adapted graphical user interfaces [GUI]
• CPC Class Codes: H04L 67/01 Protocols
• CPC Class Codes: H04L 67/10 in which an application is distributed across nodes in the network software deployment G06F8/60; multiprogramming arrangements G06F9/46

Abstract

A communication system is presented whereby sequences of video screens sent from a host CPU to a video controller can be stored and subsequently retrieved by a terminal located remote from the host CPU. The host CPU and video controller form part of a server arranged within a distributed computing system. An administrator situated at the remote terminal can retrieve select video screens produced during server operations to determine information regarding the server configuration and possible causes of server failure or future failure. The sequence of video screens thereby represent video screen changes stored upon a server controller adapted for coupling to the server expansion bus. The video screen changes represent a sequence of video screen changes occurring prior to server failure or after server reset. Those changes provide beneficial information to an administrator located remote from the server, and allows the administrator to communicate with the server using several possible communication protocols. The server controller snoops display data written from the host CPU to the video controller and mirrors the display data upon buffers within the server controller. Information within the buffers can be called upon by a remotely situated administrator regardless of whether server power is lost in the interim.

Claims

1. A computer, comprising:

a host central processing unit (CPU);

an expansion bus operably coupled between said host CPU and a video controller; and

a server controller connected to said expansion bus, wherein said server controller comprises a controller memory for storing display data forwarded from said host CPU to said video controller during a first time period prior to failure of said computer and during a second time period after reset of said computer.

2. The computer as recited in claim 1, wherein said expansion bus comprises an EISA bus.

3. The computer as recited in claim 1, wherein said video controller is coupled to a video memory such that both said video controller and said server controller are responsive to address information within a video address range for simultaneously storing said display data in both said video memory and controller memory, respectively.

4. The computer as recited in claim 1, wherein said host CPU is connected to a local CPU bus.

5. The computer as recited in claim 4, further comprising a bus interface unit coupled between said local CPU bus and said expansion bus.

6. The computer as recited in claim 1, wherein said server controller comprises detection logic coupled between said expansion bus and said controller memory for monitoring said display data forwarded across said expansion bus to said video controller and for thereafter writing said display data to said controller memory.

7. The computer as recited in claim 6, wherein said display data is forwarded across said expansion bus during times when said host CPU writes said display data to said video controller.

8. The computer as recited in claim 1, wherein said controller memory comprises:

a local frame buffer for storing a current display screen of said display data forwarded to said video controller; and

a temporary snapshot buffer coupled to receive the current display screen of said display data forwarded from said local frame buffer;

a snapshot buffer coupled to receive a previous display screen of said display data forwarded from said local frame buffer; and

comparison logic coupled between said temporary snapshot buffer and said snapshot buffer for determining a change between said previous display screen and said current display screen of said display data.

9. The computer as recited in claim 8, wherein said controller memory further comprises a current reset sequence buffer for storing said change during said second time period.

10. The computer as recited in claim 8, wherein said controller memory further comprises a current sequence buffer operably coupled to a current start buffer, and wherein said change is forwarded to said current sequence buffer and any overflow therefrom is forwarded to said current start buffer during said first time period.

11. A server controller, comprising:

detection logic adapted for coupling to a server to determine the presence of display data forwarded from the server;

a controller memory coupled to said detection logic, wherein said controller memory comprises a local frame buffer and a current reset sequence buffer; and

said local frame buffer is configured to store a current display screen of said display data, and said current reset sequence buffer is configured to store a change between the current display screen of said display data and a previous display screen of said display data during a time period after which said server receives a first reset.

12. The server controller as recited in claim 11, wherein said change between the current display screen of said display data and the previous display screen of said display data is represented as a packet of digital data.

13. The server controller as recited in claim 12, wherein said packet of digital data comprises fewer binary values than a set of binary values used in storing either the current display screen or the previous display screen.

14. The server controller as recited in claim 12, wherein said packet of digital data comprises a byte of data indicative of a character to be displayed and another byte of data indicative of attributes given to the character to be displayed, said attributes are selected from the group comprising color and intensity.

15. The server controller as recited in claim 12, wherein said packets are arranged in series representing a sequence of video screen changes which occur after said server receives the first reset.

16. The server controller as recited in claim 11, wherein said current reset sequence buffer is adapted for access by a terminal located remote from said server to display upon said terminal a sequence of video screen changes which occur after said server receives the first reset.

17. The server controller as recited in claim 11, further comprising:

a previous reset sequence buffer configured to store said change between the current display screen of said display data and the previous display screen of said display data upon the server receiving a second reset prior to the first reset; and

said previous reset sequence buffer is adapted for access by a terminal located remote from said server to display upon said terminal a sequence of video screen changes which occur after the server receives said second reset, wherein the current reset sequence buffer is adapted for access by said terminal to display upon said terminal a sequence of video screen changes which occur after said server receives the first reset.

18. A server controller, comprising:

detection logic adapted for coupling to a server to determine the presence of display data forwarded from the server;

a controller memory coupled to said detection logic, wherein said controller memory comprises a local frame buffer and a current sequence buffer; and

said local frame buffer is configured to store a current display screen of said display data, and said current sequence buffer is configured to store a change between the current display screen of said display data and a previous display screen of said display data during a time period before which said server fails.

19. The server controller as recited in claim 18, wherein said change between the current display screen of said digital data and the previous display screen of said digital data is represented as a packet of digital data.

20. The server controller as recited in claim 19, wherein said packet of digital data comprises fewer binary values than a set of binary values used in storing either the current display screen or the previous display screen.

21. The server controller as recited in claim 19, wherein said packet of digital data comprises a byte of data indicative of a character to be displayed and another byte of data indicative of attributes given to the character to be displayed, said attributes are selected from the group comprising color and intensity.

22. The server controller as recited in claim 19, wherein said packets are arranged in series representing a sequence of video screen changes which occur before said server fails.

23. The server controller as recited in claim 19, wherein said current sequence buffer is adapted for access by a terminal located remote from said server to display upon said terminal a sequence of video screen changes which occur before said server fails.

24. A method for accessing a sequence of display screens forwarded from a server to a video controller, comprising:

loading into a local frame buffer a current display screen of display data forwarded from the server to the video controller;

comparing the current display screen of display data to a previous display screen of display data previously loaded into said local frame buffer to produce a screen change packet;

repeating the steps of loading and comparing for a sequence of display screens compiled as a plurality of screen change packets which occur during a first time period immediately prior to failure of said server and during a second time period immediately after reset of said server; and

assessing said plurality of screen change packets by a terminal located remote from said server to display upon the terminal said sequence of display screens.

25. The method as recited in claim 24, wherein said loading comprises snooping an expansion bus for addresses within a specific address range sent over the expansion bus from the server.

26. The method as recited in claim 24, wherein said accessing comprises remote dialing from the terminal into a modem coupled to a buffer configured to store said plurality of screen change packets.