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Title: US5418940: Method and means for detecting partial page writes and avoiding initializing new pages on DASD in a transaction management system environment
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Country: US United States of America

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12 pages

 
Inventor: Mohan, Chandrasekaran; San Jose, CA

Assignee: International Business Machines Corporation, Armonk, NY
other patents from INTERNATIONAL BUSINESS MACHINES CORPORATION (280070) (approx. 44,393)
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Published / Filed: 1995-05-23 / 1993-08-04

Application Number: US1993000102016

IPC Code: Advanced: G06F 11/08;
IPC-7: G06F 11/00;

ECLA Code: G06F11/08; S06F201/870; T05K999/99;

U.S. Class: Current: 714/005.11; 707/999.202; 714/020;
Original: 395/575; 395/425; 395/600;

Field of Search: 395/575,425,600

Priority Number:
1993-08-04  US1993000102016

Abstract:     A method for detecting partial page writes in pages spanning multiple sectors of a sector organized multiple tracked storage facility in a page oriented, log based transaction management system. During a page write to storage from a buffer, a status bit is embedded at the end of each page sector and a status byte in the last page sector, the status byte is complemented, and each status bit is swapped with a counterpart in the status byte as it is being written out to storage. During a page read in the buffer from storage the status bit values of each page are swapped with their byte counterpart and a partial write detected as a mismatch of the bits in the status byte. Page recovery involves recreating a page from said log upon detection of either a partial sector write or a partial page write by redoing all accessing events on the log between a predetermined point to an end of log including unconditionally redoing of all format page events logged in said interval. Partial page write error is also detected where page is allocated to the buffer while avoiding a page read from storage.

Attorney, Agent or Firm: Brodie, R. Bruce ;

Primary / Asst. Examiners: Atkinson, Charles E.;

Maintenance Status: E2 Expired  Check current status

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Family: None

First Claim:
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I claim:     1. In a system for detecting error or erasure of a portion of a bit stream partitioned into an ordered set (1,2, . . . N) of N segments, the segments being recorded in any order onto a sector organized, tracked storage facility, said storage facility including means for detecting partial sector write error, wherein the improvement comprises the method steps of:
  • (a) embedding a state bit in each of the N segments and a state byte in the Nth segment;
  • (b) writing the bit stream on the storage facility including logically complementing the state byte, and as the segments of the bits stream are being written out to counterpart sectors on the facility, swapping the value of each of the state bits with the value in a counterpart position in the state byte; and
  • (c) at any time subsequent, reading the bit stream from the facility and processing the read segments including swapping the value of each of the state bits with the value in a counterpart position in the state byte, comparison matching the swapped bits of the state byte, and providing indication of error in the event of mismatch.


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Forward References: Show 37 U.S. patent(s) that reference this one

       
U.S. References: Go to Result Set: All U.S. references   |  Forward references (37)   |   Backward references (2)   |   Citation Link

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Patent  Pub.Date  Inventor Assignee   Title
Get PDF - 11pp US4298929  1981-11 Capozzi  International Business Machines Corporation Integrated multilevel storage hierarchy for a data processing system with improved channel to memory write capability
Get PDF - 12pp US4498145  1985-02 Baker et al.  International Business Machines Corporation Method for assuring atomicity of multi-row update operations in a database system
       
Foreign References: None

Other Abstract Info: DERABS G95-200045 DERG95-200045

Other References:
  • Aries: A Transaction Recovery Method Supporting Fine-Granularity Locking and Partial Rollbacks Using Write Ahead Logging vol. 17, No. 1 Feb. 7, 1992.
  • TDB vol. 25, No. 11B Apr. 1983 Partial Data Page Write Detection R. A. Crus et al.


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