Patent ID: 8386434
Filing Date: 2013-02-26
Classification: G06F,Y10S

Abstract:
1. A method comprising: receiving a block copy command that is associated with a file system; a differential snapshotter intercepting the block copy command by the file system that involves writing data to a block in a volume of a disk and performing actions, comprising: preventing the command to occur until a determination is made as to the data in the block to be written to is to be protected using a copy-on-command and when the block is to be written without using the copy-on-command; wherein the differential snapshotter takes a snapshot of the volume of the disk and that keeps a translation table and wherein the snapshotter keeps a bitmap of blocks in the volume, wherein, for a bit in the bitmap corresponding to a block in the volume, a first bit value indicates that the snapshotter does not need to protect the block by performing a copy-on-write before the block is written in response to performing the block copy command, and a second bit value indicates that the snapshotter protects the block with a copy-on-write before the block is written; and wherein performing the block copy command results in the block move from the location A on the volume to the location B on the volume.