Selective extraction of information from a mirrored image file
AssigneeNetApp, Inc.
InventorSandeep Mukherjee
Life of this patent
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Abstract
An embodiment of the invention provides a method to extract selected information from an image file selectively without requiring the user to restore, on the destination storage server, the image file which has the data for a file system. The selected information can be, for example, contents of a file, contents of a directory, other information from the image file. The selected information can be selectively extracted by reading the blocks of the file from the WAFL data structures that has been stored in the image file. An index file is generated and this index file tracks the location of VBNs (virtual block numbers) in an image file so that the user can easily obtain the selected information from disk blocks that are identified by these VBNs.
Claims17
A method comprising:
- creating a snapshot of a file system as an image file comprising chunks, wherein each chunk comprises a plurality of data blocks of the file system and a chunk header comprising volume block numbers of the plurality of data blocks;
- populating an index file with entries mapping volume block numbers specified within chunk headers to relative locations of the volume block numbers within the image file;
- receiving a request to access selected information within the image file, wherein the request specifies a volume block number of a requested data block of the selected information;
- querying the index file using the volume block number of the requested data block to identify a relative location of the volume block number within the image file;
- and
- utilizing the index file to obtain the selected information from the image file by extracting a first data portion of the image file comprising the requested data block using the relative location without extracting a second data portion of the image file.
A non-transitory machine-readable medium having stored thereon instructions for performing a method that causes a machine to:
- creating a snapshot of a file system as an image file comprising chunks, wherein each chunk comprises a plurality of data blocks of the file system and a chunk header comprising volume block numbers of the plurality of data blocks;
- populating an index file with entries mapping volume block numbers specified within chunk headers to relative locations of the volume block numbers within the image file;
- receiving a request to access selected information within the image file, wherein the request specifies a volume block number of a requested data block of the selected information;
- querying the index file using the volume block number of the requested data block to identify a relative location of the volume block number within the image file;
- and
- utilizing the index file to obtain the selected information from the image file by extracting a first data portion of the image file comprising the requested data block using the relative location without extracting a second data portion of the image file.
A computing device comprising:
- a memory containing a machine-readable medium comprising instruction for performing a method;
- and
- a processor coupled to the memory, the processor configured to execute the instructions to cause the processor to:
- creating a snapshot of a file system as an image file comprising chunks, wherein each chunk comprises a plurality of data blocks of the file system and a chunk header comprising volume block numbers of the plurality of data blocks;
- populating an index file with entries mapping volume block numbers specified within chunk headers to relative locations of the volume block numbers within the image file;
- receiving a request to access selected information within the image file, wherein the request specifies a volume block number of a requested data block of the selected information;
- querying the index file using the volume block number of the requested data block to identify a relative location of the volume block number within the image file;
- and
- utilizing the index file to obtain the selected information from the image file by extracting a first data portion of the image file comprising the requested data block using the relative location without extracting a second data portion of the image file.
Dependencies are inferred from the claim text.