Metadata for a grid based data storage system

• US 20060085594A1
• Filed: 10/20/2004
• Published: 04/20/2006
• Est. Priority Date: 10/20/2004
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Roberson, Randy L., Lubbers, Clark Edward
• Granted Patent: US 7,594,075 B2
• Time in Patent Office: Days
• US Class Current: 711/114
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 2211/1028 Distributed, i.e. distributed RAID systems with parity
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]

Abstract

Metadata architecture and associated methodology for a data storage system employing a grid-based storage capacity wherein each grid defines a storage unit in terms of a plurality of storage domains along one axis against one or more rows of a plurality of storage stripes along another axis, and wherein a grid grouping of two or more grids defines a sheet of data storage capacity. The metadata comprises identification information stored in a memory space characterizing an allocation status of the sheets in the storage capacity. A method is provided for allocating memory for the grid-based storage capacity comprising determining whether the allocation is associated with an existing logical device. If the determining step is associated with an existing logical device, then a logical device allocation map and a sheet allocation table are accessed to allocate a selected storage unit. Otherwise, a sheet allocation descriptor and a sheet allocation map are accessed to allocate a selected storage unit. A method is provided for transferring data for the grid-based storage capacity comprising accessing a logical device allocation map and a drive organization table to transfer data to or from a selected storage unit.

Claims

1. Metadata for a data storage system employing a grid-based storage capacity comprising a storage unit defined in terms of a plurality of storage domains along one axis against one or more rows of a plurality of storage stripes along another axis, and wherein a storage unit grouping of two or more storage units defines a sheet of data storage capacity, the metadata comprising identification information stored in memory characterizing an allocation status of the sheets in the storage system.

2. The metadata of claim 1 comprising a sheet allocation map characterized by an array indicating an allocatability of each of the sheets.

3. The metadata of claim 2 comprising a sheet allocation descriptor indicating the number of allocatable sheets in the storage capacity.

4. The metadata of claim 3 wherein the storage capacity is arranged into a plurality of zones, and wherein the sheet allocation descriptor indicates the number of allocatable sheets in a zone.

5. The metadata of claim 1 comprising a storage unit descriptor identifying a reference logical block address of the storage capacity for a selected storage unit.

6. The metadata of claim 5 wherein the storage unit descriptor comprises a book identification that identifies storage domains of the grid.

7. The metadata of claim 6 wherein the storage unit descriptor comprises a unique storage unit number for each storage unit in the book.

8. The metadata of claim 7 wherein the storage unit number defines the reference logical block address of the selected storage unit.

9. The metadata of claim 8 wherein the storage unit descriptor comprises fault tolerance information.

10. The metadata of claim 9 wherein the fault tolerance information comprises a drive organization indicator defining an ordered scheme of implementing spare storage domains.

11. The metadata of claim 9 wherein the storage unit descriptor comprises a redundant array of independent drives (RAID) level.

12. The metadata of claim 8 comprising a logical device allocation map characterized by an array of storage unit descriptors for each logical device in the array.

13. The metadata of claim 12 comprising a storage unit allocation descriptor characterized by an array of logical device indices indicating the number of sheets allocated to each of the logical devices.

14. The metadata of claim 13 wherein the storage unit allocation descriptor indicates the number of storage units allocated to each of the logical devices.

15. The metadata of claim 12 comprising a sheet allocation table characterized by an array indexable by sheet number indicating the logical device to which each sheet is allocated.

16. The metadata of claim 15 wherein the sheet allocation table comprises fault tolerance information.

17. The metadata of claim 10 wherein a sheet organization defines which storage domains are assigned as spares, wherein the metadata comprises a drive organization table characterized as an array of all permutations of book identifications, drive organizations, and sheet versions.

18. The metadata of claim 15 adapted for identifying one or more target storage units in response to a data storage system command by steps for managing a system configuration of the storage units in the data storage capacity.

19. The metadata of claim 18 wherein, in response to an allocation request from the data storage system, the steps for managing the system configuration comprise identifying the one or more target storage units by accessing the sheet allocation map and the sheet allocation descriptor.

20. The metadata of claim 18 wherein, in response to an allocation request from the data storage system that is associated with a logical device, the steps for managing the system configuration comprise identifying the one or more target storage units associated with the logical device by accessing the logical device allocation map and the sheet allocation table.

21. The metadata of claim 20 wherein the steps for managing the system configuration comprise identifying the one or more target storage units by accessing the sheet allocation map and the sheet allocation descriptor if there are insufficient allocatable storage units in the sheets previously allocated to the logical device.

22. A method for allocating memory for a data storage system employing a grid-based storage capacity comprising a storage unit defined in terms of a plurality of storage domains along one axis against one or more rows of a plurality of storage stripes along another axis, and wherein a storage unit grouping of two or more storage units defines a sheet of data storage capacity, the method comprising:

determining whether the allocation is associated with an existing logical device;

if the determining step is yes, then accessing a logical device allocation map and a sheet allocation table to allocate a selected storage unit; and

if the determining step is no, then accessing a sheet allocation descriptor and a sheet allocation map to allocate a selected storage unit.

23. A method for transferring data for a data storage system employing a grid-based storage capacity comprising a storage unit defined in terms of a plurality of storage domains along one axis against one or more rows of a plurality of storage stripes along another axis, and wherein a storage unit grouping of two or more storage units defines a sheet of data storage capacity, the method comprising accessing a logical device allocation map and a drive organization table to transfer data to or from a selected storage unit.