Coordinating persistent status information with multiple file servers
First Claim
1. A file server includinga set of storage devices capable of being shared with a second file server;
- a controller disposed for coupling to said shared set of storage devices;
a transceiver disposed for coupling to a communication path and for communicating messages using said communication path, said communication path using said shared set of storage devices to communicate said messages;
a takeover monitor coupled to at least part of said shared set of storage devices, and responsive to said communication path and said shared set of storage devices.
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Accused Products
Abstract
The invention provides a storage system, and a method for operating a storage system, that provides for relatively rapid and reliable takeover among a plurality of independent file servers. Each file server maintains a reliable communication path to the others. Each file server maintains its own state in reliable memory. Each file server regularly confirms the state of the other file servers. Each file server labels messages on the redundant communication paths, so as to allow other file servers to combine the redundant communication paths into a single ordered stream of messages. Each file server maintains its own state in its persistent memory and compares that state with the ordered stream of messages, so as to determine whether other file servers have progressed beyond the file server'"'"'s own last known state. Each file server uses the shared resources (such as magnetic disks) themselves as part of the redundant communication paths, so as to prevent mutual attempts at takeover of resources when each file server believes the other to have failed. Each file server provides a status report to the others when recovering from an error, so as to prevent the possibility of multiple file servers each repeatedly failing and attempting to seize the resources of the others.
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Citations
26 Claims
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1. A file server including
a set of storage devices capable of being shared with a second file server; -
a controller disposed for coupling to said shared set of storage devices; a transceiver disposed for coupling to a communication path and for communicating messages using said communication path, said communication path using said shared set of storage devices to communicate said messages; a takeover monitor coupled to at least part of said shared set of storage devices, and responsive to said communication path and said shared set of storage devices. - View Dependent Claims (2)
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3. Apparatus including
a shared resource; -
a pair of servers each coupled to said shared resource and each disposed for managing at least part of said shared resource; a communication path disposed for coupling a sequence of messages between said pair, said communication path disposed for using s aid shared resource for coupling said sequence of messages; each one of said pair being disposed for takeover of at least part of said shared resource in response to said communication path; whereby said communication path prevents both of said pair from concurrently performing said takeover. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for operating a file server, said method including steps for controlling a subset of a set of shared storage devices;
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receiving and transmitting messages with a second file server, said steps for receiving and transmitting using a communication path including said shared storage devices; monitoring said communicating path and said shared storage devices; storing state information about said file server in a persistent memory; and performing a takeover operation of said shared resource in response to said steps for monitoring and a state of said persistent memory.
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16. A method including steps for
managing at a first server at least a part of a shared resource; -
receiving and transmitting a sequence of messages between said first server to a second server, using said shared resource; performing a takeover operation at a first server of at least part of said shared resource in response to said sequence of messages; whereby said steps for receiving and transmitting prevent both of said first server and said second server from concurrently performing said takeover operation. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification