Method and apparatus for preserving data in a high-availability system preserving device characteristic data

• US 7,127,638 B1
• Filed: 12/28/2002
• Issued: 10/24/2006
• Est. Priority Date: 12/28/2002
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Bailey, Brian K., Morrissette, Keith A. P., Kubicki, Andrew, Shimkus, Joseph, Perry, Joseph A., Sardella, Steven D., Haug, Darrin
• Primary Examiner(s): Baderman, Scott
• Assistant Examiner(s): Chu, Gabriel L.
• Application Number:
  US10/330,806
• Time in Patent Office: 1,396 Days
• Field of Search: None
• US Class Current: 714/15
• CPC Class Codes: G06F 11/1441 Resetting or repowering

Abstract

In a system comprising a plurality of components, characteristic data is stored on programmable read-only-memories (PROMS) on each component. The PROMs are coupled together via a simple bus, and data is retrieved from the PROMs using the bus. The collection of data from the PROMs provides the component characteristic data, and a portion of the component characteristic data is stored in one or more persistent media devices in the system, creating a last known good copy. The persistent storage device could be any device that does not lose data in the event of a loss of power.

Claims

1. A method for retrieving component characteristic data in a system having a plurality of coupled components, the method comprising the step of:

storing characteristic data for a subset of the plurality of coupled components in a storage device on a corresponding component;

retrieving the characteristic data from the storage device at each of the components in the subset over a bus coupled to each of the components in the subset; and

storing a portion of the retrieved characteristic data in a persistent media device to provide a last known good copy of the portion of the characteristic data for the system, wherein the retrieved characteristic data includes a world wide name seed.

2. The method of claim 1 including the step of isolating the system from faults in the storage devices and the bus.

3. The method according to claim 1, wherein the portion of the characteristic data that is stored in the persistent media is considered to be critical data.

4. The method according to claim 1, wherein the characteristic data includes identity information, manufacturing information and sanity check information.

5. A method for retrieving component characteristic data in a system having a plurality of coupled components, the method comprising the step of:

storing characteristic data for a subset of the plurality of components in a storage device on the corresponding component;

retrieving the characteristic data from each of the components in the subset over a bus coupled to each of the components in the subset; and

storing a portion of the retrieved characteristic data in a persistent media device to provide a last known good copy of the portion of the characteristic data for the system, wherein the system includes at least two devices, and wherein each of the devices drives one handshake signal to and receives one handshake signal from the other one of the at least two devices on the bus.

6. The method according to claim 5 wherein the step of retrieving the characteristic data over a bus includes the step of arbitrating, by each of the devices, for access to the bus in response to the handshake signals received by each device.

7. The method according to claim 5, wherein the persistent media is a non-volatile random access memory device.

8. The method according to claim 5, wherein at least one of the components of the system is a disk drive, and wherein the persistent media used to store the characteristic data is the disk drive.

9. A system comprising:

a plurality of coupled components, wherein a subset of the plurality of coupled components each include a storage device for storing characteristic data associated with the component in which the storage device is included, wherein the characteristic data is component characteristic data selected from a group including identity data, sanity check data and manufacturing data;

a bus, coupling the storage devices of each component in the subset of components; and

persistent media, for storing a last known good copy of a portion of the characteristic data, wherein the characteristic data includes a world wide name seed.

10. The system of claim 9, wherein the subset of the plurality of components includes at least one control component, and wherein the persistent media is provided on the control component.

11. The system of claim 9, wherein the subset of the plurality of components includes at least one persistent media component, and wherein the last known good copy is stored on at least one persistent media component.

12. The system of claim 9, further comprising an isolator, coupled to the bus, to isolate the system from faults on the bus and in the storage devices.

13. The system of claim 9, wherein the bus is a serial two wire bus.

14. The system of claim 13, wherein the bus operates according to the I²C protocol.

15. The system of claim 13, wherein the bus operates according to the SMBus protocol.

16. A system comprising:

a plurality of coupled components, wherein a subset of the plurality of coupled components each include a storage device for storing characteristic data associated with the component in which the storage device is included;

a bus, coupling the storage devices of each component in the subset of components;

persistent media, for storing a last known good copy of a portion of the characteristic data; and

wherein the subset of the plurality of components includes at least one control component, the persistent media being provided on the at least one control component, wherein the control component further includes;

an input sense signal, for sensing the status of the bus;

arbitration logic, for arbitrating for control of the bus by the control component in response to the input sense signal.

17. The system of claim 16, wherein the arbitration logic further includes a back off mechanism used to prevent the control component from accessing the bus for a predetermined time period.

18. The system of claim 16, wherein the at least one control component comprises a pair of control components, each control component of the pair capable of controlling accesses to the bus, each control component comprising:

an input sense signal, coupled to the other one of the control components, to detect whether the other one of the control components is driving the bus;

an output sense signal, coupled to the other one of the control components, for communicating to the other one of the control components that the control component comprising the output sense signal communicating to the other control component is driving the bus;

arbitration logic, coupled to the input sense signal and output sense signal, for controlling accesses to the bus by the pair of control components, the arbitration logic including back off logic for preventing access to the bus by an associated control component for a predetermined period of time.

19. The system of claim 18, wherein the predetermined period of time is different for each control component.

20. A component comprising:

a storage device for storing characteristic data associated with the component;

a bus, coupled to the storage device;

means for transferring a portion of the characteristic data to persistent media to provide a last known good copy of the portion of the characteristic data,

arbitration logic, responsive to an input sensing signal, for controlling access to the bus by the component; and

an output sensing signal, for indicating to an external device a drive state of the bus by the component.

21. A method for booting an operating system in a system comprised of a plurality of interconnected components, a subset of the interconnected components each including a storage device for storing characteristic data associated with the component in which the storage device is included, the method including the step of:

retrieving characteristic data from each of the storage devices of the subset of interconnected components;

verifying that the retrieved characteristic data is valid; and

responsive to a determination that the retrieved characteristic data is valid, storing a portion of the characteristic data as a last known good copy in a persistent media, and indicating that a last known good copy of the characteristic data has been saved;

responsive to a determination that the retrieved characteristic data is not valid, determining whether a last known good copy of the portion of characteristic data has been saved in the persistent media, copying the last known good copy from the first persistent media.

22. The method according to claim 21, wherein the portion of characteristic data includes a world wide name seed.

23. The method according to claim 21, wherein the persistent media is a disk drive.