Patent ID: 7756833

Claim:
In a computing system, a method for creating a synthetic full backup of a file system, the method comprising: performing a normal full backup of a file system, the file system including data, wherein the normal full backup uses the file system to create a normal full backup dataset at create time and store the normal full backup dataset on one or more computer storage media, and wherein the normal full backup dataset is a first full backup; subsequent to performing the normal full backup, performing a partial backup of the file system to create a second backup dataset and store it on one or more computer storage media after changes to the file system, such that the first full backup is out of date, the second backup dataset including only a portion of the data of the file system, including portions of the file system changed since the normal full backup, wherein performing the partial backup of the file system to create the second backup dataset comprises differentiating whether to perform a full or partial backup of all files within the file system based on file size, wherein differentiating comprises: for all files within the file system, determining whether the files exceed a predetermined size, and: for all files determined to have a size exceeding the predetermined size, copying only changed extents within such files, such that only changes within a file, rather than an entire file, are included in the second backup dataset of the partial backup of the file system; and for all files determined to have a size less than the predetermined size, copying the entire contents of such files, such that the entire files, rather than merely changes to files, are included in the second backup dataset of the partial backup of the file system; performing a synthetic backup operation by merging the first full backup of the normal full backup with the second backup dataset to create a first synthetic full dataset of the file system and to store the first synthetic full dataset on one or more computer storage media, wherein the first synthetic full dataset is equivalent of what a normal full backup would have created if executed at create time of the first synthetic full dataset, and wherein a synthetic backup creates a full dataset based on prior backups rather than the file system; and periodically performing an additional synthetic backup operation to create a second synthetic full dataset of the file system and any changes thereto, and to store the second synthetic full data set on one or more computer storage media, and such that the first full backup is the only normal backup performed to create a full dataset.