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:
Apr. 08, 2008
Filed:
Nov. 22, 2005
Shogo Mikami, Yokohama, JP;
Shogo Mikami, Yokohama, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
The present invention is constituted so as to enable more effective backup and restoration than in the prior art. Each time a write request is issued from an applicationa PVOL is updated by writing the data contained in the issued write request to the PVOLP. In the snapshot mode, when the write frequency exceeds a frequency threshold value, the mode is switched from the snapshot mode to the journal mode. When in the snapshot mode, a snapshot of the PVOL at this point in time is acquired, either at regular or irregular intervals, for a SVOLS, and the snapshot in this SVOL becomes the restoration data. When in the journal mode, a journal comprising the data in a write request is written to a JVOLJ each time the write request is issued, and a backup, to which is applied the data in a journal written to the JVOL, is acquired when executing restoration.