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Hardware and software failover services for a file server
| Details |
Inventors: Duso, Wayne W.; Kuczynski, Leslie E.; Forecast, John; Gupta, Uday; Vahalia, Uresh K; Ting, Dennis P. J.;
Assignee: EMC Corporation (Hopkinton, MA)
Primary Examiner: Baderman; Scott
Assistant Examiner: Lohn; Joshua
Attorney, Agent or Firm: Howry Simon Arnold & White LLP
A file server includes a plurality of stream server computers linking data storage to a data network, and at least two controller servers for controlling the stream server computers. The controller servers are programmed so that at a given time one of the controller servers is active in controlling the stream server computers, and another of the controller servers is inactive. The inactive controller server is programmed to respond automatically to a failure of the active controller server by becoming active. For example, each of the controller servers has a respective flag for indicating whether or not the controller server is active. Each controller server is programmed so that, upon booting, it will read the flag of the other stream server, and if the flag of the other controller server indicates that the other controller server is active, then the controller server becomes inactive. Otherwise, the stream server assumes an active or inactive state based on a predetermined arbitration method. The active controller server also reports failure conditions to a customer service center, monitors the inactive controller server to ensure that the inactive controller server is in a state of readiness, and monitors itself to determine whether it should become inactive. |
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DETAILED DESCRIPTION The present application is directed to improvements to the failover services disclosed in Duso et al.
, U.
S.
application Ser.
No.
08/851,507 filed May 5, 1997, issued as U.
S.
Pat.
No.
5,987,621 on Nov.
16, 1999, incorporated herein by reference.
In particular, the present invention is directed to a file server that includes a plurality of stream server computers linking data storage to a data network for transfer of data streams between the data storage and the data network, and at least two controller servers for controlling the stream server computers.
The controller servers are programmed so that one of the controller servers becomes active in controlling the stream server computers, and another of the controller servers becomes inactive in controlling the stream server computers.
A controller server failover mechanism is provided for recovering from a failure of the active controller server.
The inactive controller server is programmed to respond automatically to a failure of the active controller server by becomming active in controlling the stream server computers.
In accordance with one aspect of the invention, each of the controller servers has a respective flag for indicating whether or not the controller server is active or inactive in controlling the stream server computers.
The flags, for example, are stored in local memory of the stream servers, or they are stored in the data storage.
In any case, each controller server computer can set or reset its own flag and can read the flag of the other controller server computer.
Each controller server computer is programmed so that upon booting, it will read the flag of the other controller server computer, and if the flag of the other controller server computer indicates that the other controller server computer is active in controlling the stream servers, then the controller server computer becomes inactive in controlling the steam server computers.
Otherwise, if the flag of the other controller server computer indicates that the other controller server computer is inactive, then the controller server computer assumes active or inactive status based on a predetermined arbitration method
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