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EP0541281A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Incremental-computer-file backup using signatures

Assignee: Commvault Systems Inc
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Filing: 1992-10-26
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Granted: —
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Expires: 2012-10-26
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Abstract

Abstract A facility is provided for storing in a backup memory (30-1-P) only those blocks of a file, or disk partition, which differ from corresponding blocks forming an earlier version of the file. Specifically, a file is divided into a number of blocks and a "signature" is generated for each such block. A block is then stored in the backup memory only if its associated signature differs from a signature generated for an earlier version of the block. In addition, if two blocks of the current version of the file have identical signatures and are to be stored in the backup memory, then only one of the two blocks is stored in the memory and a simple message indicating that the other block is equal to the one block is stored in the memory for the other block. Further, the application of such signatures is advantageously applied to the opposite case of restoring a file using copies of previous versions of the file that are stored in the backup memory.

Inventors

  • 👤 Arnon Kanfi

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-31 09:49
CPC Classifications
G; G06; G06F; G06F11/00; G06F11/07; G06F11/14; G06F11/1446; G06F11/1448; G06F11/1451; G06F11/08; G06F2201/00; G06F2201/835; Y; Y10; Y10S; Y10S707/00; Y10S707/99951; Y10S707/99952; Y10S707/99953; Y10S707/99954

Claims Analysis

Total Claims: 8
Claim 1
Independent Claim 72 words
Apparatus for storing a file in a memory comprising means for dividing said file into respective blocks and generating for each of said blocks a respective signature indicative of the values forming the contents of the associated block, and means for storing in said memory ones of said blocks of said file having respective signatures different from signatures generated for corresponding ones of said blocks of a prior version of said file.
Claim 2
Dependent Claim 33 words
The apparatus set forth in claim 1 wherein said means for storing includes means for causing all of said blocks to be stored in said memory if said prior signatures do not exist.
Claim 3
Dependent Claim 28 words
The apparatus set forth in claim 1 wherein the blocks of said file and blocks of said prior version of said file are associated with respective time stamps.
Claim 4
Dependent Claim 40 words
The apparatus set forth in claim 1 further comprising means for storing said signatures in a table identified by a time stamp associated with said file, said signatures being stored in said table in the order that they are generated.
Claim 5
Dependent Claim 67 words
The apparatus set forth in claim 1 wherein said means for storing includes means operative in the event that the signature generated for one of said blocks equals the signature generated for another one of said blocks and for then storing in said memory in place of said one block a message indicating that the contents of said one block equals the contents of said other block.
Claim 6
Dependent Claim 28 words
The apparatus set forth in claim 5 wherein the blocks of said file and blocks of said prior version of said file are associated with respective time stamps.
Claim 7
Dependent Claim 82 words
The apparatus set forth in claim 6 further comprising computer means associated with said memory, said computer means comprising means responsive to receipt from an originator of a request requesting a restoration of said file for unloading from said memory the blocks of said file representing earlier versions of said file that may be stored in said memory and supplying them to said originator such that said unloading is based on the reverse order that said versions were stored in said memory.
Claim 8
Dependent Claim 151 words
The apparatus set forth in claim 7 wherein groups of stored block are associated with respective versions of said file, in which the blocks forming respective ones of said groups are identified by respective block numbers, and wherein said means for unloading includes a global bit map comprising a plurality of bit locations associated with respective ones of said block numbers, means, responsive to a first one of said blocks being unloaded from said memory for setting in said bit map the bit whose location corresponds with the block number of said first block, and means, operative prior to the unloading of a second one of said stored blocks of a respective one of said groups, for preventing the unloading of said second block if its associated bit in said bit map had been set as a result of the unloading of a corresponding block of another one of said groups.

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