Method and system for storing data in an array of storage devices with additional and autonomic protection

• US 7,437,508 B2
• Filed: 12/08/2006
• Issued: 10/14/2008
• Est. Priority Date: 05/06/2004
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Hajji, Amine M.
• Primary Examiner(s): NGUYEN, THAN VINH
• Application Number:
  US11/608,787
• Publication Number:
  US 20070083709A1
• Time in Patent Office: 676 Days
• Field of Search: None
• 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 11/2007 using redundant communication media
• CPC Class Codes: G06F 11/2089 Redundant storage control functionality
• CPC Class Codes: G06F 2211/103 Hybrid, i.e. RAID systems with parity comprising a mix of RAID types
• CPC Class Codes: G06F 2211/1059 Parity-single bit-RAID5, i.e. RAID 5 implementations

Abstract

One aspect of the invention is a method for storing data in an array of storage devices. An example of the method includes writing a first strip to a first storage device and a second storage device. This example also includes writing a second strip to the second storage device and a third storage device. This example further includes writing a third strip to a third storage device and a fourth storage device.

Claims

1. A computer readable medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform operations for storing data in an array of storage devices, the operations comprising:

reserving one third of available strip LBAs for primary data, and reserving two thirds of available strip LBAs for rotated copies of data;

writing a first strip to a first storage device and a second storage device;

writing a second strip to the second storage device and a third storage device; and

writing a third strip to a third storage device and a fourth storage device.

2. A computer readable medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform operations for storing data in an array of storage devices, the operations comprising:

reserving one third of available strip LBAs for primary data, and reserving two thirds of available strip LBAs for rotated copies of data;

writing a first strip to a first storage device and a second storage device;

writing a second strip to the second storage device and a third storage device; and

writing a third strip to a third storage device and a fourth storage device;

wherein the first strip, the second strip, and the third strip, are members of a stride.

3. A computer readable medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform operations for storing data in an array of storage devices, the operations comprising:

reserving one third of available strip LBAs for primary data, and reserving two thirds of available strip LBAs for rotated copies of data;

writing a first strip to a first storage device and a second storage device;

writing a second strip to the second storage device and a third storage device; and

writing a third strip to a third storage device and a fourth storage device;

wherein at least one of the strips is a parity strip.

4. A computer readable medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform operations for storing data in an array of storage devices, the operations comprising:

reserving one third of available strip LBAs for primary data, and reserving two thirds of available strip LBAs for rotated copies of data;

writing a first strip to a first storage device, and to a second storage device, and to a third storage device;

writing a second strip to the second storage device, and to the third storage device, and to a fourth storage device; and

writing a third strip to the third storage device, and to the fourth storage device, and to a fifth storage device.

5. A computer readable medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform operations for storing data in an array of storage devices, the operations comprising:

reserving one third of available strip LBAs for primary data, and reserving two thirds of available strip LBAs for rotated copies of data;

writing a first strip to a first storage device, and to a second storage device, and to a third storage device;

writing a second strip to the second storage device, and to the third storage device, and to a fourth storage device; and

writing a third strip to the third storage device, and to the fourth storage device, and to a fifth storage device;

wherein the first strip, the second strip, and the third strip, are members of a stride.

6. A computer readable medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform operations for storing data in an array of storage devices, the operations comprising:

reserving one third of available strip LBAs for primary data, and reserving two thirds of available strip LBAs for rotated copies of data;

writing a first strip to a first storage device, and to a second storage device, and to a third storage device;

writing a second strip to the second storage device, and to the third storage device, and to a fourth storage device; and

writing a third strip to the third storage device, and to the fourth storage device, and to a fifth storage device;

wherein at least one of the strips is a parity strip.

7. A storage system, comprising:

a memory; and

a processing device coupled to the memory, wherein the processing device is programmed to perform operations for storing data in an array of storage devices, the operations comprising;

reserving one third of available strip LBAs for primary data, and reserving two thirds of available strip LBAs for rotated copies of data;

writing a first strip to a first storage device and a second storage device;

writing a second strip to the second storage device and a third storage device; and

writing a third strip to a third storage device and a fourth storage device.

8. A computer readable medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform operations for storing data in an array of storage devices, the operations comprising:

establishing a mapping table;

receiving a write command;

writing each strip of a stride to a corresponding storage device in the array of storage devices in accordance with the mapping table;

determining if a copy flag has a “

yes”

value; and

writing at least one copy of each strip of the stride to at least one corresponding storage device in the array of storage devices in accordance with the mapping table, only if the copy flag has a “

yes”

value.

9. The computer readable medium of claim 8, wherein the operations further comprise updating the mapping table.

10. A computer readable medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform operations for storing data in an array of storage devices, the operations comprising:

establishing a mapping table;

receiving a write command;

determining if a copy flag has a “

yes”

value;

and if so;

writing each strip of a stride to a corresponding storage device in the array of storage devices in accordance with the mapping table; and

writing at least one copy of each strip of the stride to at least one corresponding storage device in the array of storage devices in accordance with the mapping table;

and if not;

writing each strip of the stride to a corresponding storage device in the array of storage devices in accordance with the mapping table;

and wherein the operations further comprise updating the mapping table,

wherein the operation of updating the mapping table comprises determining if a copy flag should be set to a “

no”

value.

11. The computer readable medium of claim 10, wherein the operations further comprise:

setting a counter to an initial value; and

incrementing the counter after receiving the write command.

12. The computer readable medium of claim 11, wherein the operation of determining if a copy flag should be set to a “

no”

value comprises determining if the counter has a value that is not less than a no-copy threshold value.

13. The computer readable medium of claim 12, wherein the operations further comprise:

setting a value for a parameter N, wherein each storage device in the array of storage devices has a capacity for storing at least N strips.

14. The computer readable medium of claim 13, wherein the no-copy threshold value is a percentage of N which is a function of a mapping algorithm.

15. A computer readable medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform operations for storing data in an array of storage devices, the operations comprising:

setting a value for a parameter N, wherein each storage device in the array of storage devices has a capacity for storing at least N strips;

setting a counter to an initial value;

establishing a mapping table;

receiving a write command;

incrementing the counter;

updating the mapping table;

determining if a copy flag has a “

yes”

value;

and if so;

writing each strip of a stride and at least one copy of each strip of the stride to storage devices in the array in accordance with the mapping table, only if the copy flag has a “

yes”

value;

and if not;

writing each strip of the stride to storage devices in the array in accordance with the mapping table.

16. A storage system, comprising:

a memory; and

a processing device coupled to the memory, wherein the processing device is programmed to perform operations for storing data in an array of storage devices, the operations comprising;

establishing a mapping table;

receiving a write command;

writing each strip of the stride to a corresponding storage device in the array of storage devices in accordance with the mapping table;

determining if a copy flag has a “

yes”

value; and

writing at least one copy of each strip of the stride to at least one corresponding storage device in the array of storage devices in accordance with the mapping table, only if the copy flag has a “

yes”

value.

17. A method for storing data in an array of storage devices, the method comprising:

reserving one third of available strip LBAs for primary data, and reserving two thirds of available strip LBAs for rotated copies of data;

establishing a mapping table;

receiving a write command;

writing each strip of a stride to a corresponding storage device in the array of storage devices in accordance with the mapping table;

determining if a copy flag has a “

yes”

value; and

writing at least one copy of each strip of the stride to at least one corresponding storage device in the array of storage devices in accordance with the mapping table, only if the copy flag has a “

yes”

value.