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Abstract

A computerized data backup system and method for dynamically preserving a consistent state of primary data stored in a logical volume of a disk volume management system during processing thereof in a real-time environment. A file system command invokes a cloning of the logical volume, thereby reserving a portion for shadow-paged blocks. A read/write translation map is generated, mapping non-shadowed pages to corresponding shadowed pages in the reserved portion. Upon generating a read command for a page in the logical volume, a map search detects that a shadow page is allocated in the shadow-paged blocks corresponding to the page and effects the read. In like manner, in response to a write command to a page of the logical volume, the map is searched and a shadow page in the shadow-paged blocks is allocated if there has been no prior allocation, whereupon writing to such allocated page occurs. The backup occurs during runtime, facilitating reading from the non-shadow paged blocks during backup.

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First Claim