The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 19, 2006
Filed:
Aug. 13, 2004
Takashi Suzuki, Hiratsuka, JP;
Takashi Suzuki, Hiratsuka, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A computer system comprises a primary volumeP having a plurality of storage blocks P, and a differential volumeD having a plurality of storage blocks D. Differential data corresponding to one among the plurality of storage blocks P is stored in at least one among the plurality of storage blocks D. A control deviceidentifies differential data which is unnecessary for a host device, based on a snapshot management table S or C indicating whether data has been read by the host devicefrom any one of storage blocks P, and on a differential management tableindicating to which storage block P differential data corresponds and in which storage block D the data is stored, and performs at least one among removal of the identified differential data from the differential volumeD, and removal of an unnecessary information element from the differential management table