Method of operating a computer system

• US 5,546,534 A
• Filed: 06/01/1995
• Issued: 08/13/1996
• Est. Priority Date: 07/19/1993
• Status: Expired due to Term

• Current Assignee: CA, Inc. (d/b/a CA Technologies) (Broadcom, Inc.)
• Original Assignee: Intelligence Quotient International Ltd (Broadcom, Inc.)
• Inventors: Malcolm, Peter B.
• Primary Examiner(s): Canney, Vincent P.
• Application Number:
  US08/456,370
• Time in Patent Office: 439 Days
• Field of Search: 364/268.2, 364/269.3, 395/600, 395/700, 395/425, 395/182.04
• US Class Current: 714/6.3
• CPC Class Codes: G06F 11/1466 to make the backup process non-disruptive
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

A method of operating a computer system, in particular a micro-computer having a storage device shared between several application programs, comprises a backup process including a process for maintaining a record of changes made to the data on the storage device whilst the backup process is executing. The record is used to ensure that the data seen by the backup process does not change while it is executing whilst allowing other processes to continue to update the storage device normally thereby avoiding delays associated with file locking techniques.

The additional operations are executed at the level of the operating system interface of the microcomputer in such a manner that normal use of the computer is unaffected.

Claims

1. A method of operating a microprocessor-based computer system including a random access memory, a central processing unit and storage means, the method comprising the steps of:

providing a backup process running on the computer system and which is operable to issue a start signal and a stop signal and to perform at least one backup read operation to read original data from the storage means,

providing first instructions stored in said memory to said central processing unit to cause said central processing unit to perform at least one normal write operation to write data periodically to a primary area of said storage means, and at least one normal read operation to read data from said storage means,

after receiving said start signal, performing an interception operation to intercept said write operation, and to write data to a secondary storage area of the storage means so as to preserve the original data which would otherwise be overwritten by said write operation, maintaining a first record of said writing to the secondary area and, on performing one of said backup and normal read operations, interrogating said first record to read data from one of the primary and the secondary storage areas according to the first record, whereby the backup process is provided with preserved original data in the state it was in before said start signal was issued and including, after said start signal, keeping a second record indicative of the extent to which said backup process has progressed, and, on receipt of instructions for a write operation of said storage means, determining from said second record whether the portion of said primary area of said storage means that is to be written to has been backed up by said backup process, and, if said portion has been backed up, allowing said write operation to write to said primary area of said storage means without said write operation being intercepted.

2. A method according to claim 1, wherein the data of the normal write operation is written to said secondary area, and wherein the first record comprises a record of the intended location for said normal write operation in said primary area and a record of its actual location in said secondary area, and wherein said method further comprises the step of obtaining said preserved original data from said primary area.

3. A method according to claim 2, further comprising the steps of:

after receiving said stop signal, performing at least one restoration read operation to read data from said actual location in said secondary area and at least one restoration write operation to restore that data to its intended location in said primary area according to said first record,

when all data has been restored to its intended location in said primary area, ceasing to perform said interception operation to intercept said write operation.

4. A method according to claim 2, wherein said primary and said secondary areas are different areas of a single storage device.

5. A method according to claim 1, wherein data to be preserved is read from said primary area and written to said secondary area before the data of the normal write operation is written to said primary area, and wherein the first record comprises a record of a former location of the original data in said primary area and a record of its actual location in said secondary area, and wherein the method further comprises the step of obtaining said preserved original data from said actual location.

6. A method according to claim 5, further comprising the step of:

after receiving said stop signal, ceasing to perform said interception operation to intercept said write operation.

7. A method according to claim 5, wherein said primary and said secondary areas are different areas of a single storage device.

8. A method according to claim 1, wherein instructions associated with the interception operation are performed at the level of a basic input/output system (BIOS).

9. A method according to claim 1, wherein instructions associated with the interception operation are performed at the level of an operating system interface.

10. A method according to claim 1, wherein said start signal is issued prior to said backup process starting to perform a backup operation on said storage device and wherein said stop signal is issued after said backup process has finished said backup operation.

11. A method according to claim 1, further comprising the step of deleting, during the backup process and in response to a further write instruction, from said first record, any entries relating to portions of said primary are of said storage means which have been backed up by said backup process.

12. A method of operating a microprocessor-based computer system including an instruction memory, a central processing unit and a storage means, the method comprising the steps of:

providing a backup process, running on the computer system, which is operable to issue a start signal and a stop signal;

providing first instructions stored in said memory to said central processing unit to cause said central processing unit to perform at least one normal write operation to write data periodically to a primary storage area of said storage means; and

after receiving said start signal, performing an interception operation to intercept said write operation and, in such intercepted write operation, to write data intended for a portion of said primary storage area of said storage means to a portion of a secondary storage area of said storage means, while maintaining a record of said writing to said secondary storage area and the portion of said primary storage area to which it corresponds;

said intercepted write operation comprising the step of interrogating said record to determine whether there has been a previous intercepted write operation which concerns the writing of data intended for the same portion of said primary storage area as said current intercepted write operation, and

(a) if so, overwriting with new data that write data which was previously written to said portion of said secondary storage area of said storage means in said previous intercepted write operation, and

(b) if not, adding to said record and writing said new data to said secondary storage area;

whereby the backup process maintains a copy of the preserved original data in the state it was in before said start signal was issued.

13. A method according to claim 12, further comprising the steps of:

performing at least one restoration read operation, after receiving said stop signal, to read data from said secondary area and at least one restoration write operation to restore that data to its intended location in said primary area according to said record, and

ceasing to perform said interception operation to intercept said write operation when all data has been restored to its intended location in said primary area.

14. A method of operating a microprocessor-based computer system including an instruction memory, a central processing unit and a storage means, the method comprising the steps of:

providing a backup process, running on the computer system, which is operable to issue a start signal and a stop signal;

providing first instructions stored in said memory to said central processing unit to cause said central processing unit to perform at least one normal write operation to write data periodically to a primary storage area of said storage means; and

after receiving said start signal, performing an interception operation to intercept said write operation and, in such intercepted write operation, prior to writing new data to a portion of said primary storage area of said storage means, reading data in said portion of said primary storage area and writing it to a portion of a secondary storage area of said storage means, while maintaining a record of said writing to said secondary storage area and the portion of said primary storage area to which it corresponds;

said intercepted write operation comprising the step of interrogating said record to determine whether there has been a previous intercepted write operation which concerns the writing of data in the same portion of said primary storage area as said current intercepted write operation, and;

(a) if so, overwriting with new data that write data which was previously written in said primary storage area of said storage means in said previous intercepted write operation, and

(b) if not, reading data to be preserved from said primary storage area and writing it to said secondary storage area, adding to said record, and writing said new data to said primary storage area;

whereby the backup process maintains a copy of the preserved original data in the state it was in before said start signal was issued.

15. A method according to claim 14, further comprising the steps of:

performing at least one restoration read operation, after receiving said stop signal, to read data from said secondary area and at least one restoration write operation to restore that data to its intended location in said primary area according to said record, and

ceasing to perform said interception operation to intercept said write operation when all data has been restored to its intended location in said primary area.

16. Apparatus for operating a microprocessor-based computer system including an instruction memory, a central processing unit and a storage means, the apparatus comprising

a backup means which is operable to issue a start signal and a stop signal;

means for providing first instructions stored in said memory to said central processing unit to cause said central processing unit to perform at least one normal write operation to write data periodically to a primary storage area of said storage means; and

means, after receiving said start signal, for performing an interception operation to intercept said write operation and, in such intercepted write operation, to write data intended for a portion of said primary storage area of said storage means to a portion of a secondary storage area of said storage means, while maintaining a record of said writing to said secondary storage area and the portion of said primary storage area to which it corresponds;

said performing means further comprising means for interrogating said record to determine whether there has been a previous intercepted write operation which concerns the writing of data intended for the same portion of said primary storage area as said current intercepted write operation, and

(a) if so, overwriting with new data that write data which was previously written to said portion of said secondary storage area of said storage means in said previous intercepted write operation, and

(b) if not, adding to said record and writing said new data to said secondary storage area;

whereby the backup means maintains a copy of the preserved original data in the state it was in before said start signal was issued.

17. Apparatus for operating a microprocessor-based computer system including an instruction memory, a central processing unit and a storage means, the apparatus comprising:

a backup means which is operable to issue a start signal and a stop signal;

means for providing first instructions stored in said memory to said central processing unit to cause said central processing unit to perform at least one normal write operation to write data periodically to a primary storage area of said storage means; and

means, after receiving said start signal, for performing an interception operation to intercept said write operation and, in such intercepted write operation, prior to writing new data to a portion of said primary storage area of said storage means, reading data in said portion of said primary storage area and writing it to a portion of a secondary storage area of said storage means, while maintaining a record of said writing to said secondary storage area and the portion of said primary storage area to which it corresponds;

said performing means further comprising means for interrogating said record to determine whether there has been a previous intercepted write operation which concerns the writing in the same portion of said primary storage area as said current intercepted write operation, and

(a) if so, overwriting with new data that write data which was previously written in said primary storage area of said storage means in said previous intercepted write operation, and

(b) if not, reading data to be preserved from said primary storage area and writing it to said secondary storage area, adding to said record, and writing said new data to said primary storage area;

whereby the backup means maintains a copy of the preserved original data in the state it was in before said start signal was issued.

18. A method for providing data to a backup process executing on a microprocessor-based computer system, the system including a random access memory, a central processing unit and storage means, the method comprising the steps of:

providing first instructions stored in said memory to said central processing unit to cause said central processing unit to perform at least one normal write operation to write data periodically to a primary area of said storage means, and at least one normal read operation to read data from said storage means,

receiving a start signal from the backup process,

after receiving said start signal, performing an interception operation to intercept said write operation, and to write data to a secondary storage area of the storage means so as to preserve original data which would otherwise be overwritten by said write operation, maintaining a first record of said writing to the secondary area and, on performing one of said backup and said normal read operations, interrogating said first record to read data from one of the primary and the secondary storage area according to the first record, whereby the backup process is provided with preserved original data in the state it was in before the start signal was issued and including, keeping a second record indicative of the extent to which said backup process has progressed, and, on receipt of instructions for a write operation of said storage means, determining from said second record whether the portion of said primary area of said storage means that is to be written to has been backed up by said backup process, and, if said portion has been backed up, allowing said write operation to write to said primary area of said storage means without said write operation being intercepted.

19. A method according to claim 18, further comprising the step of deleting, during the backup process and in response to a further write instruction, from said first record, any entries relating to portions of said primary area of said storage means to which the further write instruction refers, which have been backed up by said backup process.

20. In an improved microprocessor-based computer system comprising a random access memory, a central processing unit and storage means, the improvement comprising:

means for executing a backup process operable to issue a start signal and a stop signal and to perform at least one backup read operation to read original data from said storage means,

means for causing said central processing unit to perform at least one normal write operation to write data periodically to a primary area of said storage means, and at least one normal read operation to read data from said storage means,

means for receiving said start signal,

means for performing, after receipt of said start signal, an interception operation to intercept said write operation, for writing data to a secondary storage area of said storage means so as to preserve original data which would otherwise be overwritten by said write operation, for maintaining a first record of said writing to said secondary area, and

means for interrogating said first record to read data from one of said primary and said secondary storage areas according to said first record, whereby on performance of said backup operation, said backup process is provided with preserved original data in the state it was in before said start signal was issued and including means, operable after said start signal, for keeping a second record indicative of the extent to which said backup process has progressed, and means, operative on receipt of instructions for a write operation of said storage means, to determine from said second record whether the portion of said primary area of said storage means that is to be written to has been backed up by said backup process, and, if said portion has been backed up, to allow said write operation to write to said primary area of said storage means without said write operation being intercepted.

21. The apparatus as claimed in claim 20, further comprising means, operative during said backup process and in response to a further write instruction, for deleting from said first record, any entries relating to portions of said primary area of said storage means to which said further write instruction refers, which have been backed up by said backup process.