Virtual machine data replication

Abstract

Disclosed is a method and system for selectively restoring file-level data from a disk image backup. In embodiments, a virtual machine backup may be performed by dividing a virtual machine virtual disk file into a plurality of discrete fixed-sized data blocks sharing a common index file that is stored on a backup medium, such as a hard drive, to form a backup set. Upon restoration of data from the backup set, individual blocks of the data set are compared to corresponding blocks of the target virtual machine fide. Redundant data and unchanged blocks are skipped, and only those block which have changed are restored to the target file. In this manner network bandwidth and processor resources are conserved, and replication times decreased.

1 - 17 . (canceled) 
     
     
         18 . Apparatus for performing data restoration from a backup set to a target device, comprising:
 a processor configured to operably communicate with a backup set and a target device; and   a data backup module including a set of instructions executable on the processor for performing a method of data restoration comprising the steps of:   identifying a backup data block of the backup set corresponding to a target data block of the target device;   computing a hash value corresponding to the backup data block;   determining whether the computed hash value is equal to a stored hash value corresponding to the backup data block; and   causing the backup set to be written in its entirety to the target device responsive to a determination that the computed hash value does not equal the stored hash value.   
     
     
         19 . The apparatus in accordance with  claim 18 , further comprising:
 evaluating whether a corresponding target data block has changed since a previous restoration; and   writing the backup data block to the target data block in response to an evaluation that the corresponding target data block has changed since a previous restoration.   
     
     
         20 . The apparatus in accordance with  claim 18 , wherein the determining step is performed at least in part by comparing a hash value of the backup data block to a hash value of the target data block. 
     
     
         21 . The apparatus in accordance with  claim 18 , further comprising:
 evaluating whether a corresponding target data block includes at least a portion of a file to be restored; and   writing the backup data block to the target data block in response to an evaluation that the corresponding target data block has changed since a previous restoration.   
     
     
         22 . The apparatus in accordance with  claim 18 , wherein the hash value is computed in accordance with an MD5 algorithm. 
     
     
         23 . The apparatus in accordance with  claim 18 , further comprising determining whether the first storage device virtual machine data file was previously restored. 
     
     
         24 . The apparatus in accordance with  claim 18 , wherein a virtual machine data file includes a previous restore flag. 
     
     
         25 . The apparatus in accordance with  claim 24 , wherein a previous restore flag indicates the virtual machine data file was restored at least partially from a backup set. 
     
     
         26 . The apparatus in accordance with  claim 24 , wherein the previous restore flag includes a timestamp. 
     
     
         27 . A method for restoring to a first storage device virtual machine file data from a second storage device containing a backup set of the virtual machine data file, comprising the steps of:
 identifying at least one backup set associated with a backup data block;   identifying the hash file name of the backup data block of the backup set corresponding to a file to be restored;   computing a hash value corresponding to a backup data block;   determining whether the computed hash value is equal to a stored hash value corresponding to the hash file name of a backup data block; and   causing the at least one backup set associated with a backup data block to be flagged in response to a determination that the computed hash value does not equal the stored hash value.   
     
     
         28 . The method in accordance with  claim 27 , further comprising:
 evaluating whether a target data block corresponding to a backup data block has changed since a previous restoration; and   writing the backup data block to the target data block in response to an evaluation that the corresponding target data block has changed since a previous restoration.   
     
     
         29 . The apparatus in accordance with  claim 27 , further comprising:
 evaluating whether a corresponding target data block corresponding to a backup data block includes at least a portion of a file to be restored; and   writing the backup data block to the target data block in response to an evaluation that the corresponding target data block has changed since a previous restoration.   
     
     
         30 . The method in accordance with  claim 27 , wherein the hash value is computed in accordance with an MD5 algorithm. 
     
     
         31 . The method in accordance with  claim 27 , wherein a virtual machine data file includes a previous restore flag. 
     
     
         32 . The method in accordance with  claim 31 , wherein a previous restore flag indicates the virtual machine data file was restored at least partially from a backup set. 
     
     
         33 . The method in accordance with  claim 31 , wherein the previous restore flag includes a timestamp. 
     
     
         34 . Machine-readable media comprising a set of instructions configured to perform the method in accordance with  claims 27  through  33 .