[54] NON-VOLATILE MEMORY STORAGE OF WRITE OPERATION IDENTIFIER IN DATA STORAGE DEVICE
[75] Inventors: Randy H. Katz. Berkeley; David T.
Powers. Morgan Hill; David H. Jaffe.
Belmont; Joseph S. Glider, Mountain
View; Thomas E. Idleman. Santa
Clara, all of Calif.
[73] Assignee: EMC Corporation. Hopkinton. Mass.
[21] Appl. No.: 570,163
[22] Filed: Dec 11,1995
Related U.S. Application Data
[63] Continuation of Ser. No. 224,132, Apr. 6, 1994, Pat. No. 5,475,697, which is a continuation of Ser. No. 135,362, Oct. 13, 1993. abandoned, which is a continuation of Ser. No. 966,545, Oct. 26,1992, abandoned, which is a continuation of Ser. No. 487,648, Mar. 2, 1990, Pat. No. 5,195,100.
[51] Int CI.6 G06F 11/00; H03M 13/00
[52] U.S. CI 395/182.2; 371/21.1; 365/228;
711/154
[58] Field of Search 395/182.2, 182.18,
395/182.13, 182.12; 371/21.2, 21.1; 711/154.
159
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Primary Examiner—Robert W. Beausoliel. Jr.
Assistant Examiner—Dieu-Minh Le
Attorney, Agent, or Firm—Townsend and Townsend and
Crew LLP
[57] ABSTRACT
A method and apparatus are provided for detecting and correcting various data errors that may arise in a mass data storage apparatus comprising a set of physical mass storage devices operating as one or more larger logical mass storage devices. More particularly, there is provided a method and apparatus for determining, on restoration of power to a device set, whether or not a write operation was interrupted when power was removed, and for reconstructing any data that may be inconsistent because of the removal of power.
18 Claims, 6 Drawing Sheets
