System and method for dynamically moving checksums to different memory locations

• US 20030014697A1
• Filed: 09/06/2002
• Published: 01/16/2003
• Est. Priority Date: 12/15/2000
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Hornung, Bryan, Palmer, Gregory S., Vogel, Paul F.
• Granted Patent: US 7,096,389 B2
• Time in Patent Office: Days
• US Class Current: 714/42
• CPC Class Codes: G06F 11/1048 using arrangements adapted for a specific error detection or correction feature

Abstract

A system for moving checksums within memory utilizes a plurality of memory systems and a system manager. A first memory system has a first memory location that is correlated with a checksum indicator. The checksum indicator identifies the memory system that is storing the checksum of the value presently stored at the first location. The system manager dynamically moves the checksum to a destination memory location and updates the checksum indicator such that the checksum indicator identifies the memory system of the destination memory location. While the checksum is being moved, checksum updates may occur to the memory location from which the checksum was moved. Thus, after moving the checksum, the system manager updates the checksum with the value stored at the location from which the checksum was moved. As a result, the checksum stored in the checksum destination location should be sufficiently updated to enable data recovery.

Claims

1. A system for moving checksums, comprising:

memory having a first memory location and a second memory location, said first memory location storing a checksum;

a checksum indicator identifying said one memory location; and

logic configured to move said checksum to said second memory location, said logic configured to update said checksum indicator such that said checksum indicator identifies said second memory location, said logic further configured to update said second memory location with a value retrieved from said first memory location after said checksum has been moved from said first memory location by said logic and after said checksum indicator has been updated by said logic to identify said second memory location.

2. The system of claim 1, further comprising a plurality of checksum indicators identifying said one memory location, wherein said logic is configured to disable data recoveries based on said checksum until each of said plurality of checksum indicators has been updated by said logic to identify said second memory location.

3. The system of claim 1, wherein said first and second memory locations are each associated with the same memory offset.

4. A system for dynamically moving checksums, comprising:

means for storing data values, said storing means including a plurality of memory locations;

means for executing instructions and for accessing said memory locations in response to execution of said instructions; and

means for dynamically moving a checksum from one of said memory locations to another of said memory locations, said checksum associated with at least one of said data values stored in said storing means.

5. The system of claim 4, further comprising a means for retrieving a value from said one memory location and for updating said checksum based on said retrieved value once said checksum has been moved to said other memory location.

6. The system of claim 4, wherein said one memory location and said other memory location are both associated with the same memory unit offset.

7. The system of claim 4, further comprising a checksum indicating means identifying said one memory location, wherein said moving means is configured to update said checksum indicating means such that said checksum indicating means identifies said other memory location, said moving means further configured to update said other memory location with a value retrieved from said one memory location after said checksum has been moved from said one memory location by said moving means and after said checksum indicating means has been updated by said moving means.

8. The system of claim 4, further comprising a means for recovering said at least one data value based on said checksum.

9. The system of claim 8, further comprising:

means for indicating which of said memory locations is storing said checksum;

means for updating said indicating means such that said indicating means identifies said other memory location; and

means for disabling said recovering means before said checksum is moved from said one memory location to said other memory location and until said indicating means is updated by said updating means.

10. A method for moving checksums, comprising the steps of:

storing a checksum in a first memory location;

identifying said first memory location via a checksum indicator;

moving said checksum from said first memory location to a second memory location;

updating said checksum indicator to identify said second memory location;

retrieving a value from said first memory location after said checksum has been moved from said first memory location and after said checksum indicator has been updated to identify said second memory location; and

updating said second memory location with said retrieved value.

11. The method of claim 10, further comprising the steps of:

identifying said first memory location via a plurality of checksum indicators;

updating each of said plurality of checksum indicators to identify said second memory location;

recovering a data value based on the checksum; and

disabling said recovering until said updating each of said plurality of checksum indicators is complete.