High performance data path with XOR on the fly

United States Patent [w]

Solomon et al.

US006161165A [ii] Patent Number: 6,161,165 [45] Date of Patent: *Dec. 12,2000

[73] Assignee: EMC Corporation, Hopkinton, Mass.

[ * ] Notice: This patent issued on a continued prosecution application filed under 37 CFR 1.53(d), and is subject to the twenty year patent term provisions of 35 U.S.C. 154(a)(2).

[21] Appl. No.: 08/815,193 [22] Filed: Mar. 11, 1997

Related U.S. Application Data

[63] Continuation-in-part of application No. 08/749,312, Nov. 14, 1996.

[51] Int. CI.7 G06F 12/00; G06F 13/38

[52] U.S. CI 711/114; 711/112; 711/165;

710/129

[58] Field of Search 711/114, 165,

711/112; 395/182.04, 182.05; 371/40.11, 40.14; 710/126-129; 714/7-8

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"Channel Networking: Networking Flexibility with Channel Speeds Using . . . ", Fibre Channel, http://www.ancor.com/ chnlnet.htm.

Meltek FC-Array, Product Description. http://www. meltek.com/fibre/fca.html.

Primary Examiner—-John W. Cabeca
Assistant Examiner—Pierre-Michel Bataille
Attorney, Agent, or Firm—Bromberg & Sunstein LLP

A high performance data path for performing XOR on the fly. A first memory is connected to a first bus and a second memory is connected to a second bus selectively coupled to the first bus. Logic for performing an XOR can be switched into connection with the first and second bus for XORing data in a buffer with the data passed from one of the memories to the other memory. The result is replaced into the buffer to permit successive XORing. When reading from an interrelated group of disks such as a RAID 3 group, the data path permits an N-l and go mode in which a read does not wait for data from the last disk to retrieve its data sector. If the last disk contains data (as opposed to parity) the data is obtained from the XORed data in the XOR buffer of the high performance data path. For writing data, the XOR on the fly generates the parity sector for writing at the completion of a write to an interrelated group of disks.

31 Claims, 4 Drawing Sheets