History preservation in a computer storage system

• US 7,496,555 B2
• Filed: 01/07/2004
• Issued: 02/24/2009
• Est. Priority Date: 02/26/2003
• Status: Expired due to Fees

• Current Assignee: Red Hat, Inc. (International Business Machines Corporation)
• Original Assignee: Permabit, Inc. (International Business Machines Corporation)
• Inventors: Margolus, Norman H.
• Primary Examiner(s): Vital; Pierre M
• Assistant Examiner(s): Ehichioya; Fred I
• Application Number:
  US10/752,733
• Publication Number:
  US 20040205112A1
• Time in Patent Office: 1,875 Days
• Field of Search: 707/203, 707/204, 707/206, 707/1, 707/10, 707/100, 382/116, 382/125, 382/124, 705/59, 713/16, 713/67, 713/165, 713/167, 713/168, 709/213, 709/229, 709/203, 709/218, 709/219, 709/246, 709/247, 711/161
• US Class Current: 1/1
• CPC Class Codes: G06F 16/122 using management policies backup systems G06F11/1446; file migration policies for HSM systems G06F16/185
• CPC Class Codes: G06F 16/125 characterised by the use of retention policies retention policies for HSM systems G06F16/185
• CPC Class Codes: G06F 16/2358 Change logging, detection, and notification replication G06F16/27
• CPC Class Codes: Y10S 707/99931 Database or file accessing
• CPC Class Codes: Y10S 707/99936 Pattern matching access
• CPC Class Codes: Y10S 707/99937 Sorting
• CPC Class Codes: Y10S 707/99939 Privileged access
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A method by which a disk-based distributed data storage system is organized for protecting historical records of stored data entities. The method comprises recording distinct states of an entity, corresponding to different moments of time, as separate entity versions coexisting within the distributed data storage system, and assigning expiration times to the entity versions independently within each of a plurality of storage sites according to a shared set of rules, before which times deletion is prohibited.

Claims

1. A method by which a client connected to a data repository over a lower speed network connection may provide higher speed access to a data item for application processing by an application server than is possible over the relatively low speed connection to the network, the method comprising:

determining a digital fingerprint of the data item;

testing for whether the data item is already stored in the repository by comparing the digital fingerprint of the data item to digital fingerprints of data items already in the repository;

if the data item is not already stored in the repository, transferring the data item over the lower speed connection from the client to the repository;

assigning an expiration time to the data item, before which time both modification and deletion are prohibited;

making a higher speed connection between the application server and the data repository;

executing an application on the application server to process the data item stored in the data repository; and

returning a result of the executing step to the client across the lower speed connection;

wherein the client has a plurality of data items stored in the data repository and the client controls which of the plurality of data items the application server is allowed to access;

wherein the plurality of data items are archival records of data that were persistently stored in non-volatile storage outside of the repository;

wherein, after the expiration time is assigned and before the expiration time has passed, the client can change the expiration time to a later time but no action taken by the client can cause the expiration time to be changed to an earlier time or cause the data item to be deleted; and

wherein after the expiration time has passed deletion of the data item is allowed.

2. The method of claim 1 in which the data repository comprises a plurality of storage sites and rules governing expiration and deletion are distributed to the plurality of storage sites as part of the process of storing data items.

3. The method of claim 1 in which the expiration time assigned to the data item depends upon an expiration time assigned by the client.

4. The method of claim 1 in which the data repository is a disk-based data storage system.

5. The method of claim 1 in which the application server is separate from and independent of the data repository, and is connected to it by the network.

6. The method of claim 1 in which the digital fingerprint is a cryptographic hash of the content of the data item.

7. The method of claim 1 in which the data item is encrypted using a key based on the content of the data item.

8. The method of claim 1 in which the result of the executing step is returned to the client via a Web browser.

9. The method of claim 1 in which the client is a program running on a computer and the plurality of data items are copies of data items that reside in non-volatile storage of the computer.

10. The method of claim 9 in which the application server detects a problem in the configuration of the computer, based on the plurality of data items.

11. The method of claim 1 in which the client ensures that the data item is stored in the data repository in order to provide an archival record of data stored on a storage device that is local to the client.

12. The method of claim 11 in which the data item is time stamped in a manner that allows both its contents and the time it was created to be proven.

13. The method of claim 1 in which, after the expiration time has passed, the client deletes the data item.

14. The method of claim 1 in which the data item is communicated to a client via a Web browser.

15. The method of claim 1 in which the lower speed connection is a residential-grade connection to the network and the higher connection is a commercial-grade connection to the network.

16. The method of claim 1 in which the client connected to the data repository over the lower speed network connection has only intermittent connectivity to the network and the data repository has continuous connectivity to the network.