Persistent snapshot management system

• US 20060107006A1
• Filed: 12/22/2005
• Published: 05/18/2006
• Est. Priority Date: 01/22/2002
• Status: Active Grant

• Current Assignee: Alan L. Welsh, Brian M. Mcfadden, Corinne S. Duncan, Donald D. Cross, Louis P. Witt Jr, Patricio R. Muirragui, Raymond C. Young, Richard M. Tolpin, Robbie A. Green, Zhang Kai
• Original Assignee: Alan L. Welsh, Brian M. Mcfadden, Corinne S. Duncan, Donald D. Cross, Louis P. Witt Jr, Patricio R. Muirragui, Raymond C. Young, Richard M. Tolpin, Robbie A. Green, Zhang Kai
• Inventors: Zhang, Kai, Green, Robbie A., Young, Raymond C., Tolpin, Richard M., Witt, Louis P. Jr., Welsh, Alan L., Cross, Donald D., Muirragui, Patricio R., McFadden, Brian M., Duncan, Corinne S.
• Granted Patent: US 7,237,080 B2
• Time in Patent Office: Days
• US Class Current: 711/162
• CPC Class Codes: G06F 11/1446 Point-in-time backing up or restoration of persistent data
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 12/023 Free address space management
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

A persistent snapshot is taken and maintained in accordance with a novel method and system for extended periods of time using only a portion of a computer readable medium of which the snapshot is taken. Multiple snapshots can be taken in succession at periodic intervals and maintained practically indefinitely. The snapshots are maintained even after powering down and rebooting of the computer system. The state of the object of the snapshot for each snapshot preferably is accessible via a folder on volume of the snapshot. A restore of a file or folder may be accomplished by merely copy that file or folder from the snapshot folder to a current directory of the volume. Alternatively, the entire computer system may be restored to a previous snapshot state thereof. Snapshots that occurred after the state to which the computer is restored are not lost in the restore operation. Different rule sets and scenarios can be applied to each snapshot. Furthermore, each snapshot can be written to within the context of the snapshot and later restored to its pristine condition. Software for implementing the systems and methods of snapshots in accordance with the present invention may comprise firmware of a hard disk drive controller or a disk controller board or within the HDD casing itself. The present invention further comprises novel systems and methods in which the systems and methods of taking and maintaining snapshots are utilized in creating and managing temporal data stores, including temporal database management systems. The implications for data mining and exploration, data analysis, intelligence gathering, and artificial intelligence (just to name a few areas) are profound.

Claims

1. An invention comprising a method of managing finite data storage of a temporal data store comprising one or more data groups, each data group comprising a plurality of members, data of each of which is preserved in the finite data storage, each data group having associated therewith a time point and each member of each data group having associated therewith a preservation weight, the method comprising the step of, upon detecting that consumption of the finite data storage has reached a first level, then, in order of increasing preservation weight beginning with the one or more members having the lowest preservation weight, successively deleting each member in increasing chronological order beginning with the oldest member first, until the finite data storage consumption has reached a second level.

2. A computer-readable medium having computer-readable instructions for performing the method of claim 1.

3. A computer configuration comprising computer-readable medium having computer-readable instructions for performing the method of claim 1.

4. An invention comprising a method of managing finite data storage used to store data of snapshots, each snapshot having associated therewith a snapshot time and a preservation weight, the method comprising the step of, upon detecting that consumption of the finite data storage has reached a first level, then successively deleting snapshots as a function of the preservation weights and snapshot times until the finite data storage consumption has reached a second level.

5. The invention of claim 4, further comprising the step of managing a collection of snapshots of the same object, each snapshot being taken at a different point in time and having data preserved in a finite data storage, by deleting the oldest snapshot of the collection upon the addition of a new snapshot to the collection when the number of snapshots in the collection exceeds a predetermined maximum number.

6. A computer-readable medium having computer-readable instructions for performing the method of claim 4.

7. A computer configuration comprising computer-readable medium having computer-readable instructions for performing the method of claim 4.

8. A method in which data for multiple snapshots is maintained without redundancy of preserved data for different snapshots in data storage, comprising:

determining whether a granule of a volume requires caching prior to being overwritten; and

a step for saving the granule of the volume prior to being overwritten if it needs caching.