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:
Nov. 18, 2003
Filed:
Feb. 16, 2000
Norbert P. Kusters, Woodinville, WA (US);
Luis Felipe Cabrera, Bellevue, WA (US);
Brian D. Andrew, Redmond, WA (US);
Microsoft Corporation, Redmond, WA (US);
Abstract
A system and method for more efficiently maintaining multiple temporal snapshots of a common base volume. When the base volume is modified, such as when existing data is overwritten with new data, that modification may affect two or more of the snapshots. Before the modification, the existing data is copied only to the differential file associated with the latest snapshot. When a region of a selected snapshot is read, the region is read from the selected snapshot's associated differential file. If the existing data is in the differential file, that data is returned to the reading process. If later snapshots have been taken, data associated with other parts of the region may be stored in one or more of the later differential files. If the differential file of the selected snapshot does not have data for each portion of the requested region, the mechanism continues by accessing each differential file associated with subsequent snapshots in temporal order from the earliest following the selected snapshot to the latest until either the region is complete or no later snapshots remain. Finally, if any part of the region was not filled in with data from one of the differential files, then that part of the region is read from the base volume.