Redundant peripheral device subsystem

• US 6,532,547 B1
• Filed: 06/16/1995
• Issued: 03/11/2003
• Est. Priority Date: 06/16/1995
• Status: Expired due to Term

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Wilcox, Jeffrey A.
• Primary Examiner(s): Lee, Thomas
• Assistant Examiner(s): Cao, Chun
• Application Number:
  US08/491,467
• Time in Patent Office: 2,825 Days
• Field of Search: 395/182.07, 395/183.2, 395/183.19, 395/182.01, 395/182.03, 395/182.02, 395/182.04, 395/185.09
• US Class Current: 714/5.1
• CPC Class Codes: G06F 11/2007 using redundant communication media
• CPC Class Codes: G06F 11/2025 using centralised failover control functionality
• CPC Class Codes: G06F 11/2033 switching over of hardware resources
• CPC Class Codes: G06F 11/2089 Redundant storage control functionality

Abstract

A redundant peripheral device subsystem in a computer system is disclosed including first and second peripheral device controllers. First and second peripheral device busses are coupled to the first and second peripheral device controllers, respectively. A controllable switch is coupled between the first and second peripheral device busses. The controllable switch either isolates the first and second peripheral device busses from each other, or joins them into a single peripheral device bus.

Claims

1. A redundant peripheral device subsystem in a computer system, comprising:

first and second peripheral device controllers;

first and second peripheral device busses coupled to the first and second peripheral device controllers, respectively; and

a first controllable switch, coupled between the first and second peripheral device busses, for selectively isolating the first and second peripheral device busses or joining the first and second peripheral device busses into a single peripheral device bus.

7. The subsystem of claim 1, wherein:

the first and second peripheral device busses are SCSI busses; and

the first and second peripheral device controllers are SCSI controllers.

8. The subsystem of claim 1, further comprising:

a first plurality of peripheral devices coupled to the first peripheral device bus; and

a second plurality of peripheral devices coupled to the second peripheral device bus.

9. The subsystem of claim 8, wherein:

the first and second peripheral device busses are SCSI busses;

the first and second peripheral device controllers are SCSI controllers; and

the first and second plurality of peripheral devices are SCSI disk drives.

10. The subsystem of claim 9, wherein the subsystem operates as a RAID 5 disk drive subsystem.

2. A redundant peripheral device subsystem in a computer system, comprising:

first and second peripheral device controllers;

first and second peripheral device busses coupled to the first and second peripheral device controllers, respectively; and

a first controllable switch, coupled between the first and second peripheral device busses, for selectively isolating the first and second peripheral device busses or joining the first and second peripheral device busses into a single peripheral device bus; and

a monitor controller, responsive to the first and second peripheral device controllers and coupled to the first controllable switch, for monitoring the first and second peripheral device controllers, and if one of the first and second peripheral controllers is malfunctioning, conditioning the first controllable switch to join the first and second peripheral device busses into a single peripheral device bus, otherwise conditioning the first controllable switch to isolate the first and second peripheral device busses.

3. The subsystem of claim 2, wherein the first controllable switch comprises a bidirectional FET switch.

4. A redundant peripheral device subsystem in a computer system, comprising:

first and second peripheral device controllers;

first and second peripheral device busses coupled to the first and second peripheral device controllers, respectively;

a first controllable switch, coupled between the first and second peripheral device busses, for selectively isolating the first and second peripheral device busses or joining the first and second peripheral device busses into a single peripheral device bus;

a second controllable switch, coupled between the first peripheral device controller and the first peripheral device bus, for selectively coupling the first peripheral device controller to or isolating the first peripheral device controller from the first peripheral device bus; and

a third controllable switch, coupled between the second peripheral device controller and the second peripheral device bus, for selectively coupling the second peripheral device controller to or isolating the second peripheral device controller from the second peripheral device bus.

5. The subsystem of claim 4, further comprising a monitor controller, responsive to the first and second peripheral device controllers, and coupled to the first, second and third controllable switches, for monitoring the functioning of the first and second peripheral device controllers, and if one of the first and second peripheral device controllers is malfunctioning, conditioning the first controllable switch to join the first and second peripheral device busses into a single peripheral device bus and the second and third controllable switches to isolate the malfunctioning one of the peripheral device controllers from the single peripheral device bus, otherwise conditioning the first controllable switch to isolate the first and second peripheral device busses and the second and third controllable switches to couple the first and second peripheral device controllers to the first and second peripheral device busses, respectively.

6. The subsystem of claim 4, wherein the first, second and third controllable switches respectively comprise a bidirectional FET switch.

11. A redundant peripheral device subsystem in a computer system, comprising:

first and second peripheral device busses;

a first controller board, comprising;

a first peripheral device controller;

a first controllable switch, coupled between the first peripheral device controller and the first peripheral device bus, for selectively coupling the first peripheral device controller to, or isolating the first peripheral device controller from, the first peripheral device bus; and

a second controllable switch, coupled between the first peripheral device controller and the second peripheral device bus, for selectively coupling the first peripheral device controller to, or isolating the first peripheral device controller from, the second peripheral device bus; and

a second controller board, comprising;

a second peripheral device controller;

a third controllable switch, coupled between the second peripheral device controller and the second peripheral device bus, for selectively coupling the second peripheral device controller to, or isolating the second peripheral device controller from, the second peripheral device bus; and

a fourth controllable switch, coupled between the second peripheral device controller and the first peripheral device bus, for selectively coupling the second peripheral device controller to, or isolating the second peripheral device controller from, the first peripheral device bus.

12. The subsystem of claim 11, wherein:

the first controller board further comprises a first monitor controller responsive to the first peripheral device controller and coupled to the first and second controllable switches;

the second controller board further comprises a second monitor controller responsive to the second peripheral device controller and coupled to the third and fourth controllable switches;

the subsystem further comprises an intercontroller communications path, coupled between the first and second monitor controllers;

the first monitor controller monitors the first peripheral device controller, and sends a message via the intercontroller communications path to the second monitor controller when the first peripheral device controller is malfunctioning;

the second monitor controller monitors the second peripheral device controller, and sends a message via the intercontroller communications path to the first monitor controller when the second peripheral device controller is malfunctioning;

when the first peripheral device controller is malfunctioning, the first monitor controller conditions the first and second controllable switches to isolate the first peripheral device controller from both the first and second peripheral device busses and the second monitor controller conditions the third and fourth controllable switches to join the first and second peripheral device busses to form a single peripheral device bus, and couples the second peripheral device controller to the joined single peripheral device bus;

when the second peripheral device controller is malfunctioning, the second monitor controller conditions the third and fourth controllable switches to isolate the second peripheral device controller from both the first and second peripheral device busses and the first monitor controller conditions the first and second controllable switches to join the first and second peripheral device busses to form a single peripheral device bus, and couples the first peripheral device controller to the joined single peripheral device bus;

otherwise the first monitor controller conditions the first controllable switch to couple the first peripheral device controller to the first peripheral device bus and the second controllable switch to isolate the first peripheral device controller from the second peripheral device bus, and the second monitor controller conditions the third controllable switch to couple the second peripheral device controller to the second peripheral device bus and the fourth controllable switch to isolate the second peripheral device controller from the first peripheral device bus.

13. The subsystem of claim 11, wherein the first, second, third and fourth controllable switches respectively comprise a bidirectional FET switch.

14. The subsystem of claim 11, wherein:

the first and second peripheral device busses are SCSI busses; and

the first and second peripheral device controllers are SCSI controllers.

15. The subsystem of claim 11, wherein:

a first plurality of peripheral devices are coupled to the first peripheral device bus; and

a second plurality of peripheral devices are coupled to the second peripheral device bus.

16. The subsystem of claim 15, wherein:

the first and second peripheral device busses are SCSI busses;

the first and second peripheral device controllers are SCSI controllers; and

the first and second plurality of peripheral devices are SCSI disk drives.

17. The subsystem of claim 16, wherein the subsystem operates as a RAID 5 disk drive subsystem.

18. In a computer system including a redundant peripheral device subsystem comprising first and second peripheral device controllers and first and second peripheral device busses, a method for operating the redundant peripheral device subsystem, comprising the steps of:

isolating the first peripheral device bus from the second peripheral device bus;

coupling the first peripheral device controller to the first peripheral device bus and the second peripheral device controller to the second peripheral device bus;

monitoring the operation of the first and second peripheral device controllers to detect a malfunction in one of the first and second peripheral device controllers; and

when a malfunction is detected in the one of the first and second peripheral device controllers;

joining the first and second peripheral device busses into a single peripheral device bus; and

coupling the other one of the first and second peripheral device controllers to the single peripheral device bus.

19. The method of claim 18, in which the peripheral device subsystem further comprises a controllable switch coupled between the first and second peripheral device busses, wherein:

the isolating step comprises the step of conditioning the controllable switch to open; and

the joining step comprises the step of conditioning the controllable switch to close.

20. In a computer system including a redundant peripheral device subsystem comprising first and second peripheral device controllers, first and second peripheral device busses, and a monitor controller coupled to the first and second peripheral device controllers, a method for operating the redundant peripheral device subsystem, comprising the steps of:

isolating the first peripheral device bus from the second peripheral device bus;

coupling the first peripheral device controller to the first peripheral device bus and the second peripheral device controller to the second peripheral device bus;

monitoring the operation of the first and second peripheral device controller by the monitor controller_and when a normal operation is monitored in one of the first and second peripheral device controllers, detecting a malfunction in the one of the first and second peripheral device controllers; and

when a malfunction is detected in the one of the first and second peripheral device controllers;

joining the first and second peripheral device busses into a single peripheral device bus; and

coupling the other one of the first and second peripheral device controllers to the single peripheral device bus.

21. In a computer system including a redundant peripheral device subsystem comprising first and second peripheral device controllers, first and second peripheral device busses, and a monitor controller coupled to the first and second peripheral device controllers, a method for operating the redundant peripheral device subsystem, comprising the steps of:

isolating the first peripheral device bus from the second peripheral device bus;

coupling the first peripheral device controller to the first peripheral device bus and the second peripheral device controller to the second peripheral device bus;

monitoring the operation of the first and second peripheral device controllers by the monitor controller and when an abnormal operation is monitored in one of the first and second peripheral device controllers, detecting a malfunction in the one of the first and second peripheral device controllers; and

when a malfunction is detected in one of the first and second peripheral device controllers,

isolating the one of the first and second peripheral device controllers from the single peripheral device bus;

joining the first and second peripheral device busses into a single peripheral device bus; and

coupling the other one of the first and second peripheral device controllers to the single peripheral device bus.

22. The method of claim 21 in which the peripheral device subsystem further comprises a first controllable switch coupled between the first peripheral device controller and the first peripheral device bus, and a second controllable switch coupled between the second peripheral device controller and the second peripheral device bus, wherein:

the coupling step comprises the step of conditioning both of the first and second controllable switches to close; and

the step of isolating the one of the first and second peripheral device controllers from the single peripheral device bus comprises the step of conditioning the one of the first and second controllable switches coupled to the one of the first and second peripheral device controllers to open.

23. In a computer system including a redundant peripheral device subsystem comprising first and second peripheral device controllers, first and second peripheral device busses, a first controllable switch coupled between the first peripheral device controller and the first peripheral device bus, a second controllable switch coupled between the second peripheral device controller and the second peripheral device bus, a third controllable switch coupled between the first peripheral device controller and the second peripheral device bus, and a fourth controllable switch coupled between the second peripheral device controller and the first peripheral device bus;

a method for operating the redundant peripheral device subsystem, comprising the steps of;

isolating the first peripheral device bus from the second peripheral device bus by conditioning the third and fourth controllable switches to open;

coupling the first peripheral device controller to the first peripheral device bus and the second peripheral device controller to the second peripheral device bus by conditioning the first and second controllable switches to close;

monitoring the operation of the first and second peripheral device controllers to detect a malfunction in one of the first and second peripheral device controllers; and

when a malfunction is detected in the one of the first and second peripheral device controllers;

joining the first and second peripheral device busses into a single peripheral device bus by conditioning the ones of the controllable switches coupled to the one of the peripheral device controllers to open, and the other ones of the controllable switches to close; and

coupling the other one of the first and second peripheral device controllers to the single peripheral device bus.

24. In a computer system including a redundant peripheral device subsystem comprising first and second peripheral device controllers, first and second peripheral device busses, a first monitor controller coupled to the first peripheral device controller, and a second monitor controller coupled to the second peripheral device controller and to the first monitor controller, a method for operating the redundant peripheral device subsystem, comprising the steps of:

isolating the first peripheral device bus from the second peripheral device bus;

coupling the first peripheral device controller to the first peripheral device bus and the second peripheral device controller to the second peripheral device bus;

monitoring the operation of the first and second peripheral device controllers to detect a malfunction in one of the first and second peripheral device controllers by;

monitoring the operation of the first peripheral device controller by the first monitor controller;

when an abnormal operation is monitored in the first peripheral device controller, detecting a malfunction of the first peripheral device controller and reporting it to the second monitor controller;

monitoring the operation of the second peripheral device controller by the second monitor controller; and

when an abnormal operation is monitored in the second peripheral device controller, detecting a malfunction of the second peripheral device controller and reporting it to the first monitor controller; and

when a malfunction is detected in the one of the first and second peripheral device controllers;

joining the first and second peripheral device busses into a single peripheral device bus; and

coupling the other one of the first and second peripheral device controllers to the single peripheral device bus.

25. The method of claim 24, in which the peripheral device subsystem further comprises a first controllable switch coupled between the first peripheral device controller and the first peripheral device bus, a second controllable switch coupled between the second peripheral device controller and the second peripheral device bus, a third controllable switch coupled between the first peripheral device controller and the second peripheral device bus, and a fourth controllable switch coupled between the second peripheral device controller and the first peripheral device bus, wherein:

the isolating step comprises the steps of;

conditioning the third controllable switch to open by the first monitor controller; and

conditioning the fourth controllable switch to open by the second monitor controller;

the coupling step comprises the steps of;

conditioning the first controllable switch to close by the first monitor controller; and

conditioning the second controllable switch to close by the second monitor controller; and

when a malfunction is detected in the one of the first and second peripheral device controllers;

the coupling step comprises the steps of;

conditioning the ones of the controllable switches coupled to the one of the peripheral device controllers to open by the one of the monitor controllers coupled to the one of the peripheral device controllers, in response to the detection of a malfunction by the one of the peripheral device controllers; and

the joining step comprises the steps of;

conditioning the other ones of the controllable switches to close by the other one of the monitor controllers, in response to the report of a malfunction from the one of the monitor controllers.