Mirrored memory dual controller disk storage system
First Claim
1. A computer disk storage control system adapted to be connected to a host computer, comprising:
- (a) first and second disk controllers, each having memory thereon;
(b) means for writing data directly to the first and second disk controller memory, substantially simultaneously, responsive to a single bus access by one of the first and second disk controllers, whereby a mirrored memory is obtained and maintained between the disk controllers at all points in time;
(c) means for monitoring and detecting a failure or inconsistency in the memory of either of the disk controllers, or a failure in either of the disk controllers; and
,(d) means for providing immediate and complete operational failover from one disk controller to the other upon detection of the failure.
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Accused Products
Abstract
A disk storage control system includes dual controllers having real-time, synchronous, mirrored memory therebetween to provide immediate, accurate, and reliable failover in the event of controller failure. Non-volatile random access memory provides retention of data during a loss of power and during the manipulation of hardware for purposes of repair. A communication path is established within the mirrored memory between the controllers to monitor and coordinate their activities. The state of the mirrored memory is continuously monitored for accuracy of the mirror and failure detection. Concurrent and ready access by a host computer to the same disk storage control data set from each controller is provided without need for extra manipulation or extra direct memory access (DMA) activity to satisfy host requests. Accordingly, either controller can provide immediate and reliable failover control for the disk storage system. Furthermore, either controller can be hot swapped in the event of failure without the need for preparatory intervention. Finally, a secondary controller can recover a mirror image from a failed stand alone controller memory to provide continued operations thereby so long as the mirrored memory was not the failing component.
236 Citations
19 Claims
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1. A computer disk storage control system adapted to be connected to a host computer, comprising:
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(a) first and second disk controllers, each having memory thereon; (b) means for writing data directly to the first and second disk controller memory, substantially simultaneously, responsive to a single bus access by one of the first and second disk controllers, whereby a mirrored memory is obtained and maintained between the disk controllers at all points in time; (c) means for monitoring and detecting a failure or inconsistency in the memory of either of the disk controllers, or a failure in either of the disk controllers; and
,(d) means for providing immediate and complete operational failover from one disk controller to the other upon detection of the failure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of providing operational failover in a computer disk storage control system adapted to be connected to a host computer, the disk storage control system having first and second disk controllers, each controller having memory thereon, the method comprising:
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(a) writing data directly to the first and second controller memory, substantially simultaneously, responsive to a single bus access by one of the first and second disk controllers, whereby a mirrored memory is obtained and maintained between the controllers at all points in time; (b) monitoring and detecting a failure or inconsistency in the memory of either of the controllers, or a failure in either of the controllers; and
,(c) providing immediate operational failover from one of the controllers wherein the failure was detected to the other of the controllers. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A computer readable medium having computer executable instructions for providing operational failover in a computer disk storage control system adapted to be connected to a host computer, the disk storage control system having first and second disk controllers, each controller having memory thereon, the instructions for performing the function comprising:
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(a) writing data directly to the first and second controller memory, substantially simultaneously, responsive to a single bus access by one of the first and second disk controllers, whereby a mirrored memory is obtained and maintained between the controllers at all points in time; (b) monitoring and detecting a failure or inconsistency in the memory of either of the controllers, or a failure in either of the controllers; and
,(c) providing immediate operational failover from one of the controllers wherein the failure was detected to the other of the controllers.
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Specification