Method and apparatus for ensuring data integrity

• US 6,505,307 B1
• Filed: 09/06/2000
• Issued: 01/07/2003
• Est. Priority Date: 09/06/2000
• Status: Active Grant

• Current Assignee: Unisys Corporation
• Original Assignee: Unisys Corporation
• Inventors: Thompson, James W., OʼBrien, Steven M., Leisz, Frank J., Stell, Jeffrey A.
• Primary Examiner(s): Beausoliel, Robert
• Assistant Examiner(s): Ziemer, Rita A
• Application Number:
  US09/655,730
• Time in Patent Office: 853 Days
• Field of Search: 714/6, 714/5, 714/11, 714/710, 360/369, 707/10, 707/202, 711/111, 711/114, 711/147, 711/161, 711/162, 709/217
• US Class Current: 714/6.31
• CPC Class Codes: G06F 11/0751 Error or fault detection not based on redundancy power supply failures G06F1/30; network fault management H04L41/06
• CPC Class Codes: G06F 11/2064 while ensuring consistency
• CPC Class Codes: G06F 11/2071 using a plurality of controllers

Abstract

A method and apparatus for ensuring the coherence of multiple copies of the same data at multiple geographic locations is presented. The system operating system, the system operator or some combination of both may determine the physical disks having the file or comprising the disk families containing data which requires protection. Using the MIRROR CREATE commands in a Unisys MCP operating system environment, a mirrored disk pack set is made for each relevant physical disk identified. The disk pack set is distributed amongst at least two geographic locations. For each member of each disk pack set, the STORESAFE+command associates a site identifier with the member corresponding to the member'"'"'s geographic location. During application processing, disk writes for one member of a mirrored set are performed for each member of the set. The MCP operating system checks the results of each disk write to each of the members of the mirrored disk set. If the MCP operating system determines that a write was successful for at least one member of the mirrored set at each geographic location, then a “good” I/O result is returned to the application and application processing continues normally. By contrast, if the MCP operating system determines that for least one site identifier, no member of the set assigned the identifier experienced a successful disk write, then an IOERROR is returned, and application processing may optionally be halted.

Claims

1. A method for ensuring the coherency of data used by an application executed on a host system, the host system coupled to a group of storage devices containing storage media, the storage media including at least one storage medium storing the data, the method comprising:

a. designating a plurality of the group of storage devices as a mirrored set, the plurality of the group of storage devices including a first number of storage devices located at a first geographic location and a second number of storage devices located at a second geographic location,

b. associating a first geographic site identifier with the first number of the plurality of the group of storage devices and a second geographic site identifier with the second number of the plurality of the group of storage devices; and

c. executing the application such that any input/output operations are performed for each one of the plurality of the group of storage devices and an error notification is returned unless said input/output operations are successful for at least one of the first number of plurality of the group of storage devices associated with the first geographic site identifier and at least one of the second number of the plurality of the group of storage devices associated with the second geographic site identifier.

2. The method of claim 1 wherein the first geographic identifier refers to a geographic location remote from a geographic location to which the second geographic identifier refers.

3. The method of claim 2 wherein the first geographic identifier refers to a first state located within the United States, and the second geographic identifier refers to a second state located within the United States.

4. The method of claim 1 wherein the first number and the second number are both one.

5. The method of claim 1 wherein the devices are disk devices.

6. The method of claim 5 wherein the disk devices are disk packs.

7. An apparatus for ensuring the coherency of data used by an application executed on a host system, the apparatus comprising:

a. the host system, including CPU and associated memory, the host system coupled to a mirrored set of disks comprised of members;

b. a disk mirroring software element comprised of instructions executable by the CPU and associated memory, the disk mirroring software element causing the host system to perform every disk write operation of the application for each one of the members when the disk mirroring software element is executed on the CPU; and

c. a coherency of data storage policy software element comprised of instructions executable by the CPU, the coherency of data storage policy software element causing an error notification to be returned to the application unless said every disk write operation of the application is successful for at least one of a first number of the members associated with a first geographic site identifier and at least one of a second number of the members associated with a second geographic site identifier.

8. The apparatus of claim 7 wherein the first geographic identifier refers to a geographic location remote from a geographic location to which the second geographic identifier refers.

9. The apparatus of claim 8 wherein the first geographic identifier refers to a first state located within the United States, and the second geographic identifier refers to a second state located within the United States.

10. A method for ensuring the coherency of data used by an application executed on a host system and stored on a file, the host system coupled to a group of storage devices, the method comprising:

a. determining a primary one of the group of storage devices, the primary one of the group of storage sites storing the file;

b. designating a plurality of the group of storage devices as a mirrored set, the plurality of the group of storage devices including the primary one;

c. associating a first geographic site identifier with a first number of the plurality of the group of storage devices and a second geographic site identifier with a second number of the plurality of the group of storage devices; and

d. executing the application such that any input/output operations are performed for each one of the plurality of the group of storage devices and an error notification is returned unless said input/output operations are successful for at least one of the first number of plurality of the group of storage devices associated with the first geographic site identifier and at least one of the second number of the plurality of the group of storage devices associated with the second geographic site identifier.

11. The method of claim 10 wherein the first geographic identifier refers to a geographic location remote from a geographic location to which the second geographic identifier refers.

12. The method of claim 11 wherein the first geographic identifier refers to a first state located within the United States, and the second geographic identifier refers to a second state located within the United States.

13. The method of claim 10 wherein the first number and the second number are both one.

14. The method of claim 10 wherein the storage devices are disk device sites.

15. The method of claim 14 wherein the disk device sites are disk packs.

16. A method for ensuring the coherency of data used by an application executed on a host system and stored on a family of disks, the host system coupled to a group of disks including the family of disks, the method comprising:

a. determining a plurality of disk components comprising the family of disks; and

b. for each one of the plurality of disk components,

i. designating a plurality of the group of disks as a mirrored set, the plurality of the group of disks including the one of the plurality of disk components;

ii. associating a first geographic site identifier with a first number of the plurality of the group of disks and a second geographic site identifier with a second number of the plurality of the group of disks; and

iii. executing the application such that any input/output operations are performed for each one of the plurality of the group of disks and an error notification is returned unless said input/output operations are successful for at least one of the first number of plurality of the disks associated with the first geographic site identifier and at least one of the second number of the plurality of the group of disks is associated with the second geographic site identifier.

17. The method of claim 16 wherein the first geographic identifier refers to a geographic location remote from a geographic location to which the second geographic identifier refers.

18. The method of claim 17 wherein the first geographic identifier refers to a first state located within the United States, and the second geographic identifier refers to a second state located within the United States.

19. The method of claim 16 wherein the first number and the second number are both one.

20. A method for ensuring the coherency of data used by an application executed on a host system in the event the data warrants coherency of data storage protection, the host system coupled to a group of storage devices containing storage media, the storage media including at least one storage medium storing the data, the method comprising:

a. determining whether the data warrants coherency of data storage protection; and

b. in the event the data warrants coherency of data storage protection,

i. designating a plurality of the group of storage devices as a mirrored set;

ii. associating a first geographic site identifier with a first number of the plurality of the group of storage devices and a second geographic site identifier with a second number of the plurality of the group of storage devices; and

iii. executing the application such that any input/output operations are performed for each one of the plurality of the group of storage devices and an error notification is returned unless said input/output operations are successful for at least one of the first number of plurality of the group of storage devices associated with the first geographic site identifier and at least one of the second number of the plurality of the group of storage devices associated with the second geographic site identifier.

21. A method for ensuring the coherency of data used by an application executed on a host system, the host system coupled to a group of storage devices containing storage media, the storage media including at least one storage medium storing the data, the method comprising:

a. designating a plurality of the group of storage devices as a mirrored set, the plurality of the group of storage devices including a first number of storage devices located at a first location of a computer site and a second number of storage devices located at a second location of the computer site;

b. associating a first location identifier with the first number of storage devices and a second location identifier with the second number of storage devices, the first location identifier differing from the second location identifier; and

c. executing the application such that any input/output operations are performed for each one of the plurality of the group of storage devices designated as a mirrored set and an error notification is returned unless said input/output operations are successful for at least one of the first number of storage devices associated with the first location identifier and at least one of the second number of storage devices associated with the second location identifier.

22. The method of claim 21 wherein the first number and the second number are both one.

23. The method of claim 21 wherein the devices are disk devices.

24. The method of claim 23 wherein the disk devices are disk packs.