Data reliability bit storage qualifier and logical unit metadata

• US 8,112,679 B2
• Filed: 11/25/2009
• Issued: 02/07/2012
• Est. Priority Date: 09/23/2003
• Status: Expired due to Fees

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Bean, Robert George, Lubbers, Clark Edward, Roberson, Randy L.
• Primary Examiner(s): GUYTON, PHILIP A
• Application Number:
  US12/626,183
• Publication Number:
  US 20100131706A1
• Time in Patent Office: 804 Days
• Field of Search: 714/6, 714/13, 714/15, 714/5, 714/52, 714/54, 711/114
• US Class Current: 714/54
• 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 user data is physically stored, the user data associated with redundant user data stored at another addressable storage location according to a prescribed redundancy format, and the first metadata logically appended to the user data according to the prescribed redundancy format; and

after the storing first metadata feature, satisfying a read request for the user data by retrieving the 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 user data from data stored at the another addressable storage location if the first metadata has a second value.

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

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

6. The method of claim 1 further comprising storing second metadata only at the another addressable location where the redundant user data is stored, the second metadata indicating the status of the user data.

7. The method of claim 6 wherein the second metadata indicates that the 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 user data is physically stored, the user data associated with redundant user data stored at another addressable storage location, the first metadata having a data qualifier that qualifies the user data and the redundant user data, and after storing the first metadata satisfying a read request for the user data by retrieving the user data from the addressable location where the first metadata is physically stored if the first metadata has a first value and by deriving the user data from other data stored at the another addressable storage 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 user data.

10. The apparatus of claim 8 comprising second metadata stored at the another addressable storage location indicating a status of the user data.

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

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

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

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

15. A method comprising:

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

storing second metadata only at another addressable location where associated redundant user data is stored, the second metadata indicating the status of the user data; and

after the storing first metadata and the storing the second metadata steps, satisfying a read request for the user data by retrieving the 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 user data from data stored at the another addressable location if the first metadata has a second value.

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

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

20. The method of claim 15 wherein the second metadata indicates that the user data is unreliable.