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:
Aug. 23, 2005
Filed:
Aug. 06, 2002
Philippe Armangau, Acton, MA (US);
Milena Bergant, North Grafton, MA (US);
Hongmei Wang, Shrewsbury, MA (US);
Ajay S. Potnis, South Grafton, MA (US);
Raymond A. Angelone, Norfolk, MA (US);
Philippe Armangau, Acton, MA (US);
Milena Bergant, North Grafton, MA (US);
Hongmei Wang, Shrewsbury, MA (US);
Ajay S. Potnis, South Grafton, MA (US);
Raymond A. Angelone, Norfolk, MA (US);
Abstract
A file server maintains a production file system supported by a clone volume, and multiple snapshot file systems supported by respective save volumes in a snapshot queue. Before a data block is modified for the first time after creation of the youngest snapshot, the data block is copied from the clone volume to the save volume of the youngest snapshot. A bit map indicates the blocks that have already been copied, and a block map shows the save block address for each corresponding clone block address. When a new snapshot is created, the bit and block maps are converted to a hash index that is kept linked to the save volume of what had been the youngest snapshot. When other than the oldest snapshot file system is deleted, the respective save volume is retained as a hidden object until it becomes the oldest save volume.