Fault tolerant redundant bus bridge systems and methods
First Claim
1. A fault-tolerant redundant bus bridge system for communicating between a first bus and a second bus, the system comprising:
- a first bus bridge and a second bus bridge, each configured to connect between the first and second busses, said first and second bus bridges concurrently operative to communicate between the first and second busses via respective first and second caches included therein; and
a third bus connecting said first and second bus bridges, wherein said first bus bridge, said second bus bridge and said third bus are operative to transfer information from said first bus bridge to said second cache.
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Accused Products
Abstract
First and second bus bridges, e.g., first and second RAID disk controllers, are operative to communicate between a first bus and a second bus via respective first and second caches and to transfer information from the first bus bridge to the second cache over a third bus, e.g., a synchronous data link between the caches, to allow recovery of data previously cached in the first cache via the second bus bridge. The second bus bridge preferably is operative to transfer information addressed to the first bus from the first bus to the second bus, e.g., to “alias” addresses normally assigned to the first bus bridge in event of a failure, disconnection or other change in status of the first bus bridge. The status may be communicated from the first bus bridge to the second bus bridge over a fourth bus connecting the first and second bus bridges. In one embodiment, the first and second bus bridges are included in respective first and second circuit assemblies that are connected to the first and second busses and to one another by a conductor assembly, e.g., a relatively high-reliability passive backplane. In yet another embodiment according to the present invention, a a respective one of the first and second circuit assemblies comprises a first circuit substrate configured to be releasably connected to the conductor assembly. The first circuit substrate is configured to receive a plurality of second circuit substrates for connecting the bus bridge of the circuit assembly to the first and second busses. In this manner, the circuit assemblies may be adapted to bridge a variety of bus types, such as low-voltage differential SCSI (LVDS), single-ended ended SCSI (SCSI-SE) and Fibre Channel (FC).
68 Citations
40 Claims
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1. A fault-tolerant redundant bus bridge system for communicating between a first bus and a second bus, the system comprising:
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a first bus bridge and a second bus bridge, each configured to connect between the first and second busses, said first and second bus bridges concurrently operative to communicate between the first and second busses via respective first and second caches included therein; and
a third bus connecting said first and second bus bridges, wherein said first bus bridge, said second bus bridge and said third bus are operative to transfer information from said first bus bridge to said second cache. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A fault-tolerant redundant bus bridge system for communicating between a first bus and a second bus, the system comprising:
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a conductor assembly;
a first circuit assembly connected to the first and second busses via said conductor assembly, said first circuit assembly including a first bus bridge operative to communicate between the first and second busses via a first cache included therein; and
a second circuit assembly connected to the first and second busses via said conductor assembly, said second circuit assembly including a second bus bridge operative to communicate between the first and second busses via a second cache included therein, wherein said conductor assembly connects said first and second circuit bus bridges via a third bus such that said first bus bridge, said second bus bridge and said third bus are operative to transfer information from said first bus bridge to said second cache. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
wherein said conductor assembly is configured to provide said first clock signal to said second circuit assembly;
wherein said second circuit assembly comprises;
a clock control circuit, responsive to said first clock signal, operative to determine a status of said first clock signal; and
a clock synchronizing circuit, responsive to said clock control circuit, operative to produce a clock signal synchronized to a selected one of said first and second clock signals based on the determined status of said first clock signal; and
wherein said first and second circuit assemblies are operative to transfer information from said first circuit assembly to said second SDRAM according to the synchronized clock signal.
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20. A system according to claim 8, wherein a respective one of said first and second circuit assemblies comprises:
a first circuit substrate configured to be releasably connected to said conductor assembly, said first circuit substrate configured to receive a plurality of second circuit substrates for connecting said bus bridge of said circuit assembly to the first and second busses.
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21. A system according to claim 8, wherein the first and second busses each comprise one of a Fibre Channel (FC) or a SCSI bus, and wherein a respective one of said first and second circuit assemblies are operative to communicate between the first and second busses via a PCI bus.
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22. A circuit assembly for use in a fault-tolerant redundant bus bridge system that communicates between a first bus and a second bus through a conductor assembly, the assembly comprising:
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a bus bridge configured to connect to the first and second busses through the conductor assembly and operative to communicate between the first and second busses via a cache included therein; and
a communications circuit operatively associated with said cache and operative to transfer information from said cache to a second bus bridge through said conductor assembly. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
a clock generator operative to produce a local clock signal;
a clock control circuit responsive to an external clock signal and operative to determine a status of said external clock signal; and
a clock synchronizing circuit responsive to said clock control circuit and operative to produce a clock signal that is synchronized to a selected one of the external clock signal and the local clock signal based on the determined status of said external clock signal; and
wherein said bus bridge is operative to transfer information to said SDRAM according to the synchronized clock signal.
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33. A system according to claim 22, wherein said bus bridge and second communications circuit are formed on a circuit substrate configured to receive a plurality of second circuit substrates for connecting said bus bridge to the first and second busses.
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34. A fault-tolerant method of communicating between a first bus and a second bus, the method comprising the steps of:
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connecting each of a first bus bridge and a second bus bridge between the first and second busses, said first and second bus bridges concurrently operative to communicate between the first and second busses via respective first and second caches included therein, said first and second bus bridges connected by a third bus independent of the first and second busses;
receiving information from the first bus at the first bus bridge;
caching the received information in the first cache;
transferring the received information from the first bus bridge to the second cache; and
transferring the information from the second cache to the second bus to recover information cached in the first cache. - View Dependent Claims (35, 36, 37, 38, 39, 40)
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Specification