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:
Jun. 26, 2007
Filed:
Aug. 29, 2003
Takahiro Nakano, Yokohama, JP;
Koji Sonoda, Sagamihara, JP;
Yoshiaki Eguchi, Machida, JP;
Takashi Horiuchi, Yokohama, JP;
Katsumi Hirezaki, Odawara, JP;
Takahiro Nakano, Yokohama, JP;
Koji Sonoda, Sagamihara, JP;
Yoshiaki Eguchi, Machida, JP;
Takashi Horiuchi, Yokohama, JP;
Katsumi Hirezaki, Odawara, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
Snapshots are implemented by combining original data in a place where an operational volume has been updated with data in a place where the operational volume has not been updated. A snapshot management table maintains a value indicating that update has not been conducted, or a storage place of original data, for each of combinations of blocks in the operational volume and the snapshots. If there is a snapshot in which update has not been conducted in a update place at the time of update, then original data is copied and the snapshot management table is updated. The copied original data is managed by a difference block management table, which has a value indicating whether respective snapshots are referencing the data. If a snapshot is deleted, then the value indicating that the snapshot is referencing is altered in all entries in the difference block management table.