Method and apparatus for providing a disc drive snapshot backup while allowing normal drive read, write, and buffering operations

摘要

The present invention is a method and system of performing a snapshot backup of a storage unit of a host system. The host system includes at least one primary system drive, a primary logic unit, a log system drive and at least one backup logic unit. A particular method is designed to perform the snapshot backup while allowing normal read operations and write operations to occur. After initializing the snapshot backup, the method processes a write operation of new data submitted to the primary logic unit to be written to the primary system drive during the snapshot backup by reading the old data that is on the primary system drive, buffering the old data, overwriting the old data and writing the old data to the log system drive if the write operation is the first write operation to a specific sector in the primary system drive for the snapshot backup. The method executes a read operation during the snapshot backup by processing the read operation submitted to the backup logic unit by accessing the requested data from the log system drive if the requested data is available from the log system drive, if not, accessing the requested data from the primary system drive.