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| Integrated test circuit |
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Fail-over switching system
| Details |
Inventors: Espy, James W.; Bleiweiss, Scott; Solomon, Robert C.; Bailey, Brian K.; Everdell, Peter;
Assignee: EMC Corporation (Hopkinton, MA)
Primary Examiner: Hua; Ly V.
Assistant Examiner:
Attorney, Agent or Firm: Bromberg & Sunstein LLP
A recovery method for use in a data storage system in which a plurality of data storage devices are connected to each of two communication paths. A switch may route requests to either of the two communication paths. With one data storage controller in communication with the data storage devices over a first path and a second data storage controller in communication with the data storage devices over a second path, upon detection of a malfunction on the first path, a data storage controller may request access to the other path. Thereafter, the controller may be switched into connection with the remaining operable path so as to share that path with the other controller. |
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DETAILED DESCRIPTION The present invention may be used to provide high-availability to data storage devices.
Preferred embodiments of the invention focus on allowing the interconnection of a pair of data storage controllers, each of which is connected to a separate communication path, and in which each path is in communication with an array of data storage devices.
The data storage devices each have a communication port for receiving each communication path being utilized by the invention.
In this embodiment, if the first fail-over switch is unable to communicate the data request to a storage device over the first communication path, the first fail-over switch may route the data request over the second communication path.
In preferred embodiments, a fail-over switch has several components.
There is an incoming data terminal for receiving a data request for transmission to the plurality of storage devices; an outgoing data terminal for receiving a response to the data request; a transmission terminal for communicating, over the first communication path, the data request to the plurality of storage devices; a response terminal for receiving, over the first communication path, data from the plurality of storage devices; a bypass-transmission terminal for communicating, over the second communication path, the data request to the plurality of storage devices; a bypass-response terminal for receiving, over the second communication path, data from the plurality of storage devices; and a switch that individually and selectively connects the first and second communication paths to the other terminals.
In preferred embodiments, the switch has a first bypass switch for selectively connecting the incoming data terminal to the transmission terminal or to an intermediate node, and a second bypass switch for selectively connecting the intermediate node to the bypass-transmission terminal or to the outgoing data terminal.
In a particular embodiment, the first and the second communication paths are configured as loops, where the data traveling on the loop is in one direction around the loop
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I/O Systems 
