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, 2008
Filed:
Aug. 17, 2001
Blake Lewis, Palo Alto, CA (US);
John Edwards, Sunnyvale, CA (US);
Srinivasan Viswanathan, Fremont, CA (US);
Blake Lewis, Palo Alto, CA (US);
John Edwards, Sunnyvale, CA (US);
Srinivasan Viswanathan, Fremont, CA (US);
Network Appliance, Inc., Sunnyvale, CA (US);
Abstract
The invention provides an improved method and apparatus for creating a snapshot of a file system. A 'copy-on-write' mechanism is used. The snapshot uses the same blocks as the active file system until the active file system is modified. Whenever a modification occurs, the modified data is copied to a new block and the old data is saved. In this way, the snapshot only uses space where it differs from the active file system, and the amount of work required to create the snapshot is small. A record of which blocks are being used by the snapshot is included in the snapshot itself, allowing effectively instantaneous snapshot creation and deletion. A snapshot can also be deleted instantaneously simply by discarding its root inode.