Patent ID: 8051044

Claim:
A computer system providing online continuous data protection, the computer system comprising: a storage device storing block data; a backup storage device storing block data; and wherein the computer system is operable to: creating a single bitmap of data storage blocks on the storage device that are subject to an initial backup; copying blocks marked in the bitmap as an initial backup to the backup storage device; in case of error when accessing the storage device, indicating in the bitmap, that the data storage block that caused the error is invalid; creating an editable incremental backup on the backup storage device, such as that any block in the editable incremental backup is subject to being rewritten so long as the editable incremental backup is open; and during the creation of the editable incremental backup, intercepting a write command directed to a data storage block marked in the bitmap and redirecting the write command to the editable incremental backup on the backup storage device, and for data that is to be written in the write command, writing the data to editable incremental backup on the backup storage by executing the redirected write command, wherein, if the data block that is the subject of the write command was backed up in a latest incremental backup, replacing the old data block in the latest incremental backup with the data block that is the subject of the write command, wherein the latest incremental backup reflects latest changed data on the data storage device; and after intercepting the write command, duplicating the write command on the data storage device.