Method for creating consistent backup image of a storage volume without requiring a snapshot

Abstract

Method for creating a consistent image, on a destination volume, of a target volume that remains in production use while the image is being created, without requiring the use of a snapshot.

I claim: 
     
         1 . A method for creating a consistent image of a target volume under control of an operating system running on a machine, said target volume comprising a plurality of data blocks, wherein said target volume remains available for read and write operations during the period that such consistent image is being created, said method comprising:
 (a) copying all of the data in the target volume to a destination volume without regard to changes in the data while it was being copied;   (b) maintaining a record identifying those data blocks on the target volume that have changed since the beginning of the most recent prior step (a) or step (c);   (c) copying to the destination volume those data blocks identified by said record as having changed on the target volume since the beginning of the most recent prior step (a) or step (c), in such manner as to replace any prior representation of those blocks on the destination volume; and   (d) repeating steps (b) and (c) until said record shows no changed blocks on the target volume.