Method and apparatus for establishing and maintain

专利名称：Method and apparatus for establishing and

maintaining the status of membership setsused in mirrored read and writeinput/output without logging

发明人：Luis Felipe Cabrera,Darrell Don Earl Long申请号：US08/690214申请日：19960726公开号：US05917998A公开日：19990629

摘要：A method and apparatus that maintains in stable storage an identification ofwhich copies in a mirrored disk system are currently up to date without requiring the useof a logging mechanism. The invention may include a plurality of mirrored disk drives anda processing unit for controlling the writing and reading of data units to and frommirrored disk drives, wherein the processing unit establishes and maintains cohort setsfor each mirrored disk drive. The cohort set represents the status of copies of the dataunits stored on the mirrored disk drives and contains membership information forredundant copies of data units stored in the plurality of mirrored disk drives. The

membership information comprises a data structure of 2n status bits for identifying whichdisks contain current copies of the data units, where n is the number of disks in thesystem, and wherein the first n bits are used to indicate an intention to update themembership information for the copies and the second n bits are used indicate a currentstate of the membership information. The data structure may further include log(n)additional bits for identifying each mirrored disk.

申请人：INTERNATIONAL BUSINESS MACHINES CORPORATION

代理机构：Merchant, Gould, Smith, Edell, Welter & Schmidt, P

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