DATA RELIABILITY BIT STORAGE QUALIFIER AND LOGICAL UNIT METADATA

• US 20100131706A1
• Filed: 11/25/2009
• Published: 05/27/2010
• Est. Priority Date: 09/23/2003
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Lubbers, Clark EDWARD, Bean, Robert George, Roberson, Randy L.
• Granted Patent: US 8,112,679 B2
• Time in Patent Office: Days
• US Class Current: 711/114
• CPC Class Codes: G06F 11/008 Reliability or availability analysis
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 2211/104 Metadata, i.e. metadata associated with RAID systems with parity

Abstract

Apparatus and associated method that stores first metadata only at the same addressable storage location of a computer readable medium as that where associated first user data is stored, and afterward satisfies a read request for the first user data by retrieving the first user data from the addressable location of the computer readable medium where the first metadata is stored if the first metadata has a first value, and by reconstructing the first user data from other metadata stored at another addressable location of the computer readable medium than where the first metadata is stored if the first metadata has a second value.

Claims

1. A method comprising:

storing first metadata only at the same addressable storage location of a computer readable medium as that where associated first user data is stored; and

after the storing first metadata step, satisfying a read request for the first user data by retrieving the first user data from the addressable location of the computer readable medium where the first metadata is stored if the first metadata has a first value, and by reconstructing the first user data from other metadata stored at another addressable location of the computer readable medium than where the first metadata is stored if the first metadata has a second value.

2. The method of claim 1 wherein the first metadata indicates a reliability of the first user data.

3. The method of claim 1 wherein the first metadata is a data reliability qualifier bit.

4. The method of claim 1 wherein the first metadata is embedded with the first user data.

5. The method of claim 1 wherein the first metadata is appended with the first user data.

6. The method of claim 1 further comprising the step of storing second metadata only at another addressable location of the computer readable medium where associated second user data is stored, the second metadata indicating the status of the first user data.

7. The method of claim 6 wherein the second metadata indicates that the first user data is unreliable.

8. An apparatus comprising:

a computer readable medium having a plurality of addressable storage locations; and

circuitry configured to store first metadata only at the same addressable storage location as that where associated first user data is stored, and after storing the first metadata satisfying a read request for the first user data by retrieving the first user data from the addressable location where the first metadata is stored if the first metadata has a first value and by deriving the first user data from other metadata stored at another addressable location than where the first metadata is stored if the first metadata has a second value.

9. The apparatus of claim 8 wherein the circuitry includes a controller that operably stores the first metadata with the first user data.

10. The apparatus of claim 8 wherein at least another of the storage locations includes second metadata stored with associated second user data at another addressable storage location that is, in turn, associated with the first user data, wherein the first metadata indicates a status of the second user data.

11. The apparatus of claim 10 wherein the storage locations areas are in a RAID configuration.

12. The apparatus of claim 8 wherein the first metadata is appended to the first user data.

13. The apparatus of claim 8 wherein the first metadata is embedded in the first user data.

14. The apparatus of claim 8 wherein the first metadata and the first user data are generated by the same function.

15. A method:

storing first metadata only at the same addressable storage location of a computer readable medium as that where associated first user data is stored; and

after the storing first metadata step, satisfying a read request for the first user data by retrieving the first user data from the addressable location of the computer readable medium where the first metadata is stored if the first metadata has a first value, and by regenerating the first user data from other metadata stored at another addressable location of the computer readable medium than where the first metadata is stored if the first metadata has a second value.

16. The method of claim 15 wherein the first metadata indicates a reliability of the first user data.

17. The method of claim 15 wherein the first metadata is a data reliability qualifier bit.

18. The method of claim 15 wherein the first metadata is embedded with the first user data.

19. The method of claim 15 wherein the first metadata is appended with the first user data.

20. The method of claim 15 further comprising the step of storing second metadata only at another addressable location of the computer readable medium where associated second user data is stored, the second metadata indicating the status of the first user data.

21. The method of claim 20 wherein the second metadata indicates that the first user data is unreliable.