Patent ID: 6393538
Filing Date: 2002-05-21
Classification: G06F,Y10S

Abstract:
A remote transfer method used in a file system comprising a primary file unit connected to a host apparatus to be data-updated by said host apparatus, and a secondary file unit connected to said primary file unit to be data-updated by said primary file unit,said remote transfer method being a method for transferring data from said primary file unit to said secondary file unit in order to write into said secondary file unit data which is same as data written into said primary file unit by said host apparatus, when said host apparatus writes data into said primary file unit by issuing a writing operation directive command for transferring writing start location information to said primary file unit as data and successively issuing a series of write commands, which configures one write access unit together with the write operation directive command, to said primary file unit one by one, said remote transfer method comprising: receiving a writing operation directive command, which is issued by said host apparatus to transfer writing start location information to said primary file unit as data, in said primary file unit; transferring the received writing operation directive command from said primary file unit to said secondary file unit, when said primary file unit receives said writing operation directive command from said host apparatus, to direct to start the writing; transferring said writing start location information as data from said primary file unit to said secondary file unit; giving, from said primary file unit to said host apparatus, notice that transferring said writing start location information has been normally transferred, when said primary file unit confirms that said writing start location information has been normally received by said secondary file unit, to cause said host apparatus to issue a series of write commands, which configures one write access unit together with said writing operation directive command; receiving one of said series of write commands in said primary file unit; transferring the received write command from said primary file unit to said secondary file unit, each time said primary file unit receives one of said series of write commands from said host apparatus after said writing operation directive command, to direct the writing; transferring data to be written by the write command from said primary file unit to said secondary file unit; and giving, from said primary file unit to said host apparatus, notice that the writing by the write command has been normally terminated, when said primary file unit confirms that data written in said primary file unit by the write command has been normally written in said secondary file unit, to cause said host apparatus to issue a next write command.