United States Patent 6871271
 

Incrementally restoring a mass storage device to a prior state

US Patent Issued on March 22, 2005
 

Inventor(s)


Assignee


Application

No. 29189 filed on 2001-12-20

Current US Class

711/162 , Backup 707/204 , Archiving or backup 711/161 , Archiving 711/167 , Access timing 714/6 Redundant stored data accessed (e.g., duplicated data, error correction coded data, or other parity-type data)

Field of Search

707/204 , Archiving or backup 711/102 , Solid-state read only memory (ROM) 711/103 , Programmable read only memory (PROM, EEPROM, etc.) 711/104 , Solid-state random access memory (RAM) 711/111 , Accessing dynamic storage device 711/112 , Direct access storage device (DASD) 711/161 , Archiving 711/162 , Backup 711/167 , Access timing 714/6 Redundant stored data accessed (e.g., duplicated data, error correction coded data, or other parity-type data)

Examiners


Attorney, Agent or Firm


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Abstract Claims Description Full Text

Abstract
Restoring a mass storage device, including the corresponding data blocks stored thereon, to a state in which it existed at a prior instant in time to minimize the data loss caused by data blocks becoming corrupt or lost. After a mirrored or backup copy has been made, data blocks that are to be overwritten in response to a write request are stored in a preservation memory prior to being overwritten. The data blocks stored in the preservation memory are time-stamped to designate the chronological order by which the data blocks were overwritten. If data becomes corrupted, the data blocks of the preservation memory are applied to the corrupted data in reverse chronological order until such time that a valid, non-corrupted set of data is obtained. In this manner, data more recent than that associated with the full mirrored or backup copy can be reconstructed.
Other References
  • IBM Corp, IBM Technical Disclosure Bulletin, Storage Management Mechanism for Managing Snapshot Pages, pp. 26-29, Sep. 1992, author unknown.
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