Storage optimization of pre-allocated units of storage
Disclosed herein are systems, methods, and processes to optimize the storage of pre-allocated units of storage during a backup operation. Null units of storage are identified in pre-allocated units of storage prior to the backup operation. Upon being identified, the null units of storage are inhibited from being written to a backup image during the backup operation.
1. A method, implemented in a computer system, comprising:
retrieving, by a processor of the computer system, a backup image from a storage device associated with the computer system, wherein
the backup image is for a pre-allocated data file,
the backup image comprises a map file and one or more live data blocks, and
the map file identifies one or more null units of storage of the pre-allocated data file at least by virtue of comprising metadata;
reading, by the processor, the metadata from the backup image, wherein
the metadata is associated with the one or more live data blocks by virtue of comprising live block metadata;
retrieving, by the processor, the one or more live data blocks from the backup image; and
restoring, by the processor, the pre-allocated data file to a restored data file, wherein
the restoring uses the metadata and the one or more live data blocks, and
the restoring comprises
generating, by the processor, one or more null data blocks, and
recreating, by the processor, the pre-allocated data file using the one or more live data blocks, the one or more null data blocks, and the metadata.
2. The method of claim 1 , wherein
the metadata indicates whether a given block of the pre-allocated data file is a null data block or a live data block, and
the method further comprises
recreating the given block of the restored data file by writing a null data block of the one or more null data blocks or a live data block of the one or more live data blocks, as indicated by the metadata.
3. The method of claim 1 , wherein
the map file comprises null block metadata that identifies the one or more null units of storage of the pre-allocated data file.
4. The method of claim 3 , wherein the restoring further comprises:
accessing the map file, wherein
the map file was used in creating the backup image by inhibiting writing of the one or more null units of storage by virtue of identifying the one or more null units of storage.
5. The method of claim 4 , further comprising:
detecting a restoration request, wherein
the restoration request is a request for restoration of the pre-allocated data file from the backup image.
6. The method of claim 5 , further comprising:
serving the restoration request by providing the restored data file.
7. The method of claim 1 , wherein
the one or more null data blocks are generated using the metadata.
8. The method of claim 1 , wherein the recreating comprises:
reading at least a portion of the metadata;
determining whether a given block of the pre-allocated data file is a null data block or a live data block;
in response to the at least the portion of the metadata indicating that the given block was live data, restoring a live block of data from the one or more live data blocks into a position of the given block in the restored data file; and
in response to the at least the portion of the metadata indicating that the given block was not live data, inserting a null block into the position of the given block in the restored data file.
9. The method of claim 8 , wherein the recreating further comprises:
determining a starting point, wherein
the starting point is defined as an offset in the pre-allocated data file,
the at least a portion of the metadata indicates the offset; and
setting the start point as the starting point for the recreating.
10. A computer system comprising:
one or more processors;
a non-transitory computer-readable storage medium coupled to the one or more processors; and
a plurality of instructions, encoded in the non-transitory computer-readable storage medium and configured to cause the one or more processors to
retrieve a backup image from a storage device associated with the computer system, wherein
the backup image is for a pre-allocated data file,
the backup image comprises a map file and one or more live data blocks, and
the map file identifies one or more null units of storage of the pre-allocated data file at least by virtue of comprising metadata,
read metadata from the backup image, wherein
the metadata is associated with the one or more live data blocks by virtue of comprising live block metadata,
retrieve the one or more live data blocks from the backup image, and
restore the pre-allocated data file to a restored data file, wherein
the plurality of instructions configured to cause the one or more processors to restore uses the metadata and the one or more live data blocks, and
the plurality of instructions configured to cause the one or more processors to restore comprise instructions configured to cause the one or more processors to
generate one or more null data blocks, and
recreate the pre-allocated data file using the one or more live data blocks, the one or more null data blocks, and the metadata.
11. The computer system of claim 10 , wherein
the backup image is stored in the non-transitory computer-readable storage medium.
12. The computer system of claim 10 , wherein
the metadata indicates whether a given block of the pre-allocated data file is a null data block or a live data block, and
the plurality of instructions configured to cause the one or more processors to recreate is further configured to cause the one or more processors to
recreate the given block of the restored data file by writing a null data block of the one or more null data blocks or a live data block of the one or more live data blocks, as indicated by the metadata.
13. The computer system of claim 10 , wherein
the map file comprises null block metadata that identifies the one or more null units of storage of the pre-allocated data file.
14. The computer system of claim 13 , wherein the plurality of instructions configured to cause the one or more processors to restore is further configured to cause the one or more processors to:
access the map file, wherein
the map file was used in creating the backup image by inhibiting writing of the one or more null units of storage by virtue of identifying the one or more null units of storage.
15. The computer system of claim 13 , wherein the plurality of instructions configured to cause the one or more processors to recreate the pre-allocated data file is further configured to cause the one or more processors to:
read at least a portion of the metadata;
determine whether a given block of the pre-allocated data file is a null data block or a live data block;
in response to the at least the portion of the metadata indicating that the given block was live data, restore a live block of data from the one or more live data blocks into a position of the given block in the restored data file; and
in response to the at least the portion of the metadata indicating that the given block was not live data, insert a null block into the position of the given block in the restored data file.
16. A computer program product comprising:
a plurality of instructions, comprising
a first set of instructions, executable on a computer system, configured to retrieve a backup image from a storage device associated with the computer system, wherein
the backup image is for a pre-allocated data file,
the backup image comprises a map file and one or more live data blocks, and
the map file identifies one or more null units of storage of the pre-allocated data file at least by virtue of comprising metadata,
a second set of instructions, executable on the computer system, configured to read metadata from the backup image, wherein
the metadata is associated with the one or more live data blocks by virtue of comprising live block metadata,
a third set of instructions, executable on the computer system, configured to retrieve the one or more live data blocks from the backup image, and
a fourth set of instructions, executable on the computer system, configured to restore the pre-allocated data file to a restored data file, wherein
the fourth set of instructions uses the metadata and the one or more live data blocks, and
the fourth set of instructions comprise
a first subset of instructions, executable on the computer system, configured to generate one or more null data blocks, and
a second subset of instructions, executable on the computer system, configured to recreate the pre-allocated data file using the one or more live data blocks, the one or more null data blocks, and the metadata; and
a non-transitory computer-readable storage medium, wherein the instructions are encoded in the non-transitory computer-readable storage medium.
17. The computer program product of claim 16 , wherein the metadata indicates whether a given block of the pre-allocated data file is a null data block or a live data block, and the second subset of instructions comprise:
a first sub-subset of instructions, executable on the computer system, configured to recreate the given block of the restored data file by writing a null data block of the one or more null data blocks or a live data block of the one or more live data blocks, as indicated by the metadata.
18. The computer program product of claim 16 , wherein
the map file comprises null block metadata that identifies the one or more null units of storage of the pre-allocated data file.
19. The computer program product of claim 18 , wherein the fourth set of instructions comprises:
a first sub-subset of instructions, executable on the computer system, configured to access the map file, wherein
the map file was used in creating the backup image by inhibiting writing of the one or more null units of storage by virtue of identifying the one or more null units of storage.
20. The computer program product of claim 16 , wherein the fourth set of instructions comprises:
a first subset of instructions, executable on the computer system, configured to reading at least a portion of the metadata;
a second subset of instructions, executable on the computer system, configured to determining whether a given block of the pre-allocated data file is a null data block or a live data block;
a third subset of instructions, executable on the computer system, configured to, in response to the at least the portion of the metadata indicating that the given block was live data, restoring a live block of data from the one or more live data blocks into a position of the given block in the restored data file; and
a fourth subset of instructions, executable on the computer system, configured to, in response to the at least the portion of the metadata indicating that the given block was not live data, inserting a null block into the position of the given block in the restored data file.