Patent ID: 7536507
Filing Date: 2009-05-19
Classification: G06F

Abstract:
1. A method for preserving an atomic write to a disk array, the method comprising: (a) storing portions of a file in paired locations on a disk array such that a first location of a location pair for a file portion stores scratch data for the file portion and a second portion of the location pair for the file portion stores valid data for the file portion and storing a bitmap on the disk array, the bitmap having bits indicating whether valid data for each file portion resides in the first or the second location for its respective location pair; (b) receiving a write request to write data to a portion of the file being less than the entire file, wherein the bitmap indicates that valid data for the portion of the file to be written to resides in a first memory location of one of the location pairs on the disk array, and, in response: (c) receiving a request to save the modification, and, in response to the request to save the modified data, replacing the bitmap stored on the disk array with the modified bitmap.