Method for reducing magnetic storage volume for computer disk image backup
First Claim
1. A method of copying information stored on a first medium to a second medium, said information being stored on said first medium as a plurality of blocks, said method comprising the steps of:
- determining ones of said plurality of blocks stored on said first medium that contain data,generating a data structure which records an indication of each of said determined ones of said plurality of blocks,reading said data structure to determine a first range of contiguous blocks as recorded in said data structure and copying to said second medium said first range of said plurality of blocks as recorded in said read data structure.
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Accused Products
Abstract
A computer data backup method where copying of data blocks from one medium to another is deferred until a data structure, e.g. a bit map, is generated defining those data blocks that in fact contain data. The data structure is then read to copy to the backup medium the data-containing blocks as defined by the data structure. Since the data structure is generated before the copying is effected, a range of contiguous data-containing blocks is determinable such that all the blocks of that contiguous range may be copied as a single continuous operation. The magnitude of required backup storage is reduced by eliminating the copying of empty blocks in general unless the number of empty blocks between two ranges of contiguous data-containing blocks is less than a predefined number.
77 Citations
19 Claims
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1. A method of copying information stored on a first medium to a second medium, said information being stored on said first medium as a plurality of blocks, said method comprising the steps of:
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determining ones of said plurality of blocks stored on said first medium that contain data, generating a data structure which records an indication of each of said determined ones of said plurality of blocks, reading said data structure to determine a first range of contiguous blocks as recorded in said data structure and copying to said second medium said first range of said plurality of blocks as recorded in said read data structure. - View Dependent Claims (2, 3, 4)
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5. A method of copying information stored on a first medium to a second medium, said information being stored on said first medium as a plurality of blocks, said method comprising
determining ones of said plurality of blocks stored on said first medium that contain data, generating a bit map recording an indication of each of said determined ones of said plurality of blocks, said indications comprising a given binary value in positions of said bit map corresponding to the location of said determined ones of said plurality of blocks stored on said first medium, and reading said generated bit map and copying to said second medium ones of said plurality of blocks from locations on said first medium corresponding to positions of said read bit map having said given binary value.
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9. A method of copying information stored on a computer disk to a magnetic tape, said information being stored on said computer disk as a plurality of blocks, said method comprising
a. determining ones of said plurality of blocks stored on said computer disk that contain data, b. generating a bit map which records an indication of each of said determined ones of said plurality of blocks, said indications comprising a given binary value in each position of said bit map corresponding to the locations of said determined ones of said plurality of blocks on said computer disk, c. determining a first range of contiguous blocks having said given binary value in the corresponding contiguous positions of said bit map. d. determining a second range of contiguous blocks having said given binary value in the corresponding contiguous positions of said bit map, e. determining a number of blocks between said first range and said second range, f. comparing said determined number to a predefined number, g. when the determined number is less than said predefined number, concatenating said first range, said blocks having said other binary value and said second range, as said first range and repeating steps d, e and f, h. when the determined number is not less than said predefined number, copying said first range to said magnetic tape, and i. repeating steps c through h.
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11. A method of copying information stored on a computer disk to a magnetic tape, said information being stored on said computer disk as a plurality of blocks, said method comprising
a. determining ones of said plurality of blocks stored on said computer disk that contain data, b. generating a bit map which records an indication of each of said determined ones of said plurality of blocks, said indications comprising a given binary value in positions of said bit map corresponding to the locations of said determined ones of said plurality of blocks on said computer disk, c. storing said bit map on said magnetic tape, d. determining a range of contiguous blocks having said given binary value in the corresponding contiguous positions of said bit map, e. copying said determined first range of contiguous blocks to said magnetic tape, f. repeating steps d and e, reading said bit map stored on said magnetic tape, and copying said determined ones of said plurality of blocks that contain data from said magnetic tape to said computer disk at locations corresponding to positions of said read bit map having said given binary value.
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12. A method of copying information stored on a first medium to a second medium, said information being stored on said first medium as a plurality of files, said files being organized into one or more file systems, each of said one or more file systems including a list of file descriptors associating one of said files with one of said one or more file systems, each of said file descriptors including a list of data blocks associated with said file, said data blocks storing information on said first medium, said method including the steps of:
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determining ones of said one or more file systems to copy to a second medium; for each determined file system, generating a bit map by sequentially reading the file descriptor list for said each determined file system, and for each file descriptor, setting a bit in said bit map, wherein said bit'"'"'s position in said bit map corresponds to the address of each data block listed in the file descriptor, reading the bit map for each determined file system and copying to said second medium data blocks as indicated by said bits in said bit map. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A method of copying information stored on a computer disk to a magnetic tape, said information being stored on said computer disk as a plurality of files, said files being organized into one or more file systems, each of said one or more file systems including a list of file descriptors associating one of said files with one of said one or more file systems, each of said file descriptors including a list of data blocks storing information on said computer disk associated with said file, said method comprising the steps of:
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a. determining ones of said one or more file systems to copy to said tape, b. for each determined file system, generating a bit map by sequentially reading the file descriptor list associated with said determined file system and setting a bit in said bit map to a given binary value in positions of said bit map corresponding to said data blocks listed in each of said file descriptors, c. determining a first range of contiguous blocks having said given binary value by reading said bit map, d. determining a second range of contiguous blocks having said given binary value by reading said bit map, e. determining a number of blocks having a binary value other than said given binary value between said first range and said second range, f. comparing said determined number to a predetermined number, g. when the determined number is less than said predetermined number, concatenating said first range, said blocks having said other binary value and said second range as said first range and repeating steps d, e and f, h. when the determined number is not less than said predefined number, copying said first range to said magnetic tape, and i. repeating steps c through h for each determined file system.
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19. A method of copying information stored on a computer disk to a magnetic tape, said information being stored on said computer disk as a plurality of files, said files being organized into one or more file systems, each of said one or more file systems including a list of file descriptors associating one of said files with one of said one or more file systems, each of said file descriptors including a list of data blocks storing information on said computer disk associated with said file, said method comprising the steps of:
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a. determining ones of said one or more file systems to copy to said tape, b. for each determined file system, generating a bit map by sequentially reading the file descriptor list associated with said determined file system and setting a bit in said bit map having a given binary value in positions of said bit map corresponding to said data blocks listed in each of said file descriptors, c. storing said bit map on said tape, d. determining a range of contiguous blocks having said given binary value by reading said bit map, e. copying said range to said magnetic tape, and f. repeating steps d and e for each determined file system, g. reading said stored bit map, and h. copying said ranges from said magnetic tape to said computer disk at locations corresponding to positions of said read bit map having said given binary value.
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Specification