Computer backup system operable with open files

• US 5,675,725 A
• Filed: 06/06/1995
• Issued: 10/07/1997
• Est. Priority Date: 07/19/1993
• Status: Expired due to Term

• Current Assignee: CA, Inc. (d/b/a CA Technologies) (Broadcom, Inc.)
• Original Assignee: Cheyenne Advanced Technology Limited (Broadcom, Inc.)
• Inventors: Malcolm, Peter B.
• Primary Examiner(s): Canney, Vincent P.
• Application Number:
  US08/465,925
• Time in Patent Office: 854 Days
• Field of Search: 395/182.04, 395/425, 395/450, 364/260.2, 364/268.7, 364/268.2, 364/282.1
• US Class Current: 714/6.12
• 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

Abstract

A backup program for a computer system with a hard disk maintains a record of changes made to the data in a file being backed up. During backup both the original and update file portions or records are stored, and the backup program reads the original data while other applications read the updated data. To identify whether a read operation is initiated by the backup program or by another application, the system determines, using the stack, the source of the read request. Alternatively it interrogates the user, process or task id. Access to the file by the backup program is guaranteed by manipulating the System File Table. It is ensured that the file is in a `good` state by delaying the start of the backup operation for a predetermined period.

Claims

1. 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 said computer system, which is operable to issue a start signal and a stop signal and to issue at least one backup read instruction to read original data from said storage means;

delaying the issue of a start signal until any series of write operations to a file to be backed up have been completed;

providing first instructions stored in said memory to said central processing unit to cause said central processing unit to perform at least one normal read operation to read data from said storage means, said backup process being capable of operating with files which are open to access by said instructions;

providing file opening means for opening a file to be read by a normal read operation and having a denying function for denying access to said file by other read operations;

disabling said denying function of said file opening means to permit simultaneous read access to said file by a backup read operation and a normal read operation;

maintaining a record of data written to said storage means, to relate corresponding areas in a primary storage area of said storage means and a secondary storage area of said storage means;

determining, after receiving said start signal and on receiving a read instruction, whether said read instruction relates to a backup read operation or a normal read operation, and on performing one of said backup and normal read operations, interrogating said record to read data from one of said primary and said secondary storage areas according to said record, and on performing the other of said backup and normal read operations, reading data from said primary storage area; and

wherein the step of determining whether the read instruction relates to a backup read operation or a normal read operation comprises the step of looking at the area of memory from which said read instruction originates to determine the identity of the program which initiated said read instruction.

2. A method of operating a microprocessor-based computer system including an instruction memory, a central processing unit and a storage means, in a computer network;

the method comprising the steps of;

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

delaying the issue of a start signal until any series of write operations to a file to be backed up have been completed;

providing first instructions stored in said memory to said central processing unit to cause said central processing unit to perform at least one normal read operation to read data from said storage means, said backup process being capable of operating with files which are open to access by said instructions;

providing file opening means for opening a file to be read by a normal read operation and having a denying function for denying access to said file by other read operations;

disabling said denying function of said file opening means to permit simultaneous read access to said file by a backup read operation and a normal read operation;

maintaining a record of data written to said storage means, to relate corresponding areas in a primary storage area of said storage means and a secondary storage area of said storage means;

determining, after receiving said start signal and on receiving a read instruction, whether said read instruction relates to a backup read operation or a normal read operation, and on performing one of said backup and normal read operations, interrogating said record to read data from one of said primary and said secondary storage areas according to said record, and on performing the other of said backup and normal read operations, reading data from said primary storage area; and

allocating to said backup process a user, process or task identification, said step of determining whether said read instruction relates to a backup read operation or a normal read operation comprising determining whether said read operation is requested by a user or program with said user, process or task identification.

3. 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 said computer system, which is operable to issue a start signal and a stop signal and to issue at least one backup read instruction to read original data from said 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 read operation to read data from said storage means;

maintaining a record of data written to said storage means, to relate corresponding areas in a primary storage area of said storage means and a secondary storage area of said storage means; and

determining, after receiving said start signal and on receiving a read instruction, whether said read instruction relates to a backup read operation or a normal read operation, and on performing one of said backup and normal read operations, interrogating said record to read data from one of said primary and said secondary storage areas according to said record, and on performing the other of said backup and normal read operations, reading data from said primary storage area;

wherein the step of determining whether said read instruction relates to a backup read operation or a normal read operation comprises the step of looking at the area of memory from which said read instruction originates to determine the identity of the program which initiated said read instruction.

4. A method as claimed in claim 3, in which said looking step comprises interrogating a stack to determine locations stored on the stack and interrogating said locations.

5. A method as claimed in claim 4, in which said looking step comprises comparing code around said locations with code expected from the backup program.

6. A method as claimed in claim 4, in which said looking step comprises determining a Program Segment Prefix and an Environment String associated with the program at said locations, and determining the program name using said Environment String.

7. A method of operating a microprocessor-based computer system including an instruction memory, a central processing unit and a storage means, in a computer network;

the method comprising the steps of;

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

maintaining a record of data written to said storage means, to relate corresponding areas in a primary storage area of said storage means and a secondary storage area of said storage means; and

determining, after receiving said start signal and on receiving a read instruction, whether said read instruction relates to a backup read operation or a normal read operation, and on performing one of said backup and normal read operations, interrogating said record to read data from one of said primary and said secondary storage areas according to said record, and on performing the other of said backup and normal read operations, reading data from said primary storage area; and

wherein the improvement comprises allocating to said backup process a user, process or task identification, whereby said step of determining whether the read instruction relates to a backup read operation or a normal read operation comprises determining whether said read operation is requested by a user or program with said user, process or task identification.

8. A method of operating a microprocessor-based computer system including an instruction memory, a central processing unit and a storage means, said 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 and to perform at lest one backup read operation to read original data from said storage means; and

providing instructions stored in said memory to said central processing unit to cause said central processing unit to perform at least one normal read operation to read data from said storage means; and

providing file opening means for opening a file to be read by a normal read operation and denying access to said file by other read operations;

wherein the improvement comprises providing means associated with said backup process which disables said denying function of said file opening means to permit simultaneous read access to said file by a backup read operation and a normal read operation.

9. A method as claimed in claim 8, in which said computer system maintains a table of open files, and in which the denying function is disabled by temporarily reversibly altering the table.

10. 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 said computer system, 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 said storage means; and

providing 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 to said storage means; and

in which said backup process is capable of operating with files which are open to access by said instructions,

wherein the improvement comprises the step of delaying the issue of a start signal until any series of write operations to a file to be backed up have been completed.

11. In a microprocessor-based computer system including an instruction memory, a central processing unit and a storage means;

a backup system comprising;

a backup program, for running on said computer system, which is operable to issue a start signal and a stop signal and to issue at least one backup read instruction to read original data from said storage means;

means for delaying the issue of a start signal until any series of write operations to a file to be backed up have been completed;

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 read operation to read data from said storage means, said backup program being capable of operating with files which are open to access by said instructions;

file opening means for opening a file to be read by a normal read operation and having a denying function for denying access to said file by other read operations;

means for disabling said denying function of said file opening means to permit simultaneous read access to said file by a backup read operation and a normal read operation;

means for maintaining a record of data written to said storage means, to relate corresponding areas in a primary storage area of said storage means and a secondary storage area of said storage means;

means for determining, after receiving said start signal and on receiving a read instruction, whether said read instruction relates to a backup read operation or a normal read operation, and on performing one of said backup and normal read operations, interrogating said record to read data from one of said primary and said secondary storage areas according to said record, and on performing the other of said backup and normal read operations, reading data from said primary storage area; and

wherein the means for determining whether the read instruction relates to a backup read operation or a normal read operation comprises means for looking at the area of memory from which said read instruction originates to determine the identity of the program which initiated said read instruction.

12. In a computer network, a microprocessor-based computer system including an instruction memory, a central processing unit and a storage means;

the microprocessor-based computer system comprising;

a backup program, for running on said computer system, which is operable to issue a start signal and a stop signal and to issue an least one backup read instruction to read original data from said storage means;

means for delaying the issue of a start signal until any series of write operations to a file to be backed up have been completed;

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 read operation to read data from said storage means, said backup program being capable of operating with files which are open to access by said instructions;

file opening means for opening a file to be read by a normal read operation and having a denying function for denying access to said file by other read operations;

means for disabling said denying function of said file opening means to permit simultaneous read access to said file by a backup read operation and a normal read operation;

means for maintaining a record of data written to said storage means, to relate corresponding areas in a primary storage area of said storage means and a secondary storage area of said storage means;

means for determining, after receiving said start signal and on receiving a read instruction, whether said read instruction relates to a backup read operation or a normal read operation, and on performing one of said backup and normal read operations, interrogating said record to read data from one of said primary and said secondary storage areas according to said record, and on performing the other of said backup and normal read operations, reading data from said primary storage area; and

means for allocating to said backup program a user, process or task identification, said means for determining whether said read instruction relates to a backup read operation or a normal read operation comprising means for determining whether said read operation is requested by a user or program with said user, process or task identification.

13. In a microprocessor-based computer system including an instruction memory, a central processing unit and a storage means, a backup system comprising:

a backup program, for running on said computer system, which is operable to issue a start signal and a stop signal and to issue at least one backup read instruction to read original data from said storage means;

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 read operation to read data from said storage means;

means for maintaining a record of data written to said storage means, to relate corresponding areas in a primary storage area of said storage means and a secondary storage area of said storage means; and

means for determining, after receiving said start signal and on receiving a read instruction, whether said read instruction relates to a backup read operation or a normal read operation, and on performing one of said backup and normal read operations, interrogating said record to read data from one of said primary and said secondary storage areas according to said record, and on performing the other of said backup and normal read operations, reading data from said primary storage area;

wherein the means for determining whether said read instruction relates to a backup read operation or a normal read operation comprises means for looking at the area of memory from which said read instruction originates to determine the identity of the program which initiated said read instruction.

14. A system as claimed in claim 13, in which said looking means comprises means for interrogating a stack to determine locations stored on the stack and interrogating said locations.

15. A system as claimed in claim 14, in which said looking means comprises means for comparing code around said locations with code expected from the backup program.

16. A system as claimed in claim 14, in which said looking means comprises means for determining a Program Segment Prefix and an Environment String associated with the program at said locations, and determining the program name using said Environment String.

17. In a computer network, a microprocessor-based computer system including an instruction memory, a central processing unit and a storage means;

the microprocessor-based computer system comprising;

a backup program, for running on said computer system, which is operable to issue a start signal and a stop signal and to issue at least one backup read instruction to read original data from said storage means;

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 read operation to read data from said storage means;

means for maintaining a record of data written to said storage means, to relate corresponding areas in a primary storage area of said storage means and a secondary storage area of said storage means; and

means for determining, after receiving said start signal and on receiving a read instruction, whether said read instruction relates to a backup read operation or a normal read operation, and on performing one of said backup and normal read operations, interrogating said record to read data from one of said primary and said secondary storage areas according to said record, and on performing the other of said backup and normal read operations, reading data from said primary storage area; and

wherein the improvement comprises means for allocating to said backup program a user, process or task identification, whereby said means for determining whether the read instruction relates to a backup read operation or a normal read operation comprises means for determining whether said read operation is requested by a user or program with said user, process or task identification.

18. In a microprocessor-based computer system including an instruction memory, a central processing unit and a storage means, a backup system comprising:

a backup program, for running on the computer system, which is operable to issue a start signal and a stop signal and to perform at lest one backup read operation to read original data from said storage means; and

means for providing instructions stored in said memory to said central processing unit to cause said central processing unit to perform at least one normal read operation to read data from said storage means; and

file opening means for opening a file to be read by a normal read operation and denying access to said file by other read operations;

wherein the improvement comprises means associated with said backup program for disabling said denying function of said file opening means to permit simultaneous read access to said file by a backup read operation and a normal read operation.

19. A system as claimed in claim 18, in which said computer system maintains a table of open files, and in which the denying function is disabled by temporarily reversibly altering the table.

20. In a microprocessor-based computer system including an instruction memory, a central processing unit and a storage means, a backup system comprising:

a backup program, for running on said computer system, 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 said storage means; and

means for providing 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 to said storage means; and

in which said backup program is capable of operating with files which are open to access by said instructions,

wherein the improvement comprises means for delaying the issue of a start signal until any series of write operations to a file to be backed up have been completed.