Method and apparatus for expansion, contraction, and reapportionment of structured external storage structures

• US 5,581,737 A
• Filed: 09/12/1994
• Issued: 12/03/1996
• Est. Priority Date: 09/12/1994
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Palmer, Stewart L., King, Richard P., Dahlen, Dennis J., Elko, David A., Nick, Jeffrey M., Wilkinson, Wendell W., Helffrich, Audrey A.
• Primary Examiner(s): Swann, Tod R.
• Assistant Examiner(s): PEIKARI, BEHZAD
• Application Number:
  US08/304,458
• Time in Patent Office: 813 Days
• Field of Search: 395/600, 395/700, 395/497.01, 395/497.02, 395/497.03, 364/DIG. 1
• US Class Current: 711/170
• CPC Class Codes: G06F 12/023 Free address space management
• CPC Class Codes: G06F 12/0815 Cache consistency protocols
• CPC Class Codes: G06F 12/084 with a shared cache

Abstract

A method and apparatus for optimizing a data structure of an external data storage facility shared by a plurality of data processing systems, the data structure being allocated by a first allocation command which includes first allocation parameters based on an amount of storage space in the external data storage facility assigned for creation of the data structure and a composition of the data structure, includes a device for determining values of the first allocation parameters, to thereby determine a first composition of the data structure, a device for determining an actual usage of the data structure, to thereby determine a second composition of the data structure, a device for comparing the first composition of the data structure with the second composition of the data structure, and a device for issuing, based on an output from the comparing device, a second allocation command having second allocation parameters, to the data structure for reallocation thereof. The issuing device includes a device for adjusting the first composition of the data structure to the second composition, as storage space in the external data storage facility and processing cycles become available to execute the second allocation parameters. Until the second allocation parameters are achieved, the reallocation of the data structure remains pending and all processing commands are accepted and processed by the external data storage facility.

Claims

1. An apparatus for optimizing a data structure of an external data storage facility shared by a plurality of data processing systems, said data structure being allocated by a first allocation command which includes first allocation parameters based on an amount of storage space in said external data storage facility assigned for creation of said data structure and a composition of said data structure, said apparatus comprising:

means for determining values of said first allocation parameters, to thereby determine a first composition of said data structure;

means for determining an actual usage of said data structure, to thereby determine a second composition of said data structure;

means for comparing said first composition of said data structure with said second composition of said data structure; and

means for issuing, responsive to an output from said comparing means, a second allocation command having second allocation parameters, to said data structure for reallocation thereof,

said issuing means including means for adjusting said first composition of said data structure to said second composition, as storage space in said external data storage facility and processing cycles become available to execute said second allocation parameters,

wherein, until said second allocation parameters are achieved, the reallocation of said data structure remains pending and all processing commands are accepted and processed by said external data storage facility.

2. An apparatus according to claim 1, wherein said adjusting means includes means for expanding a size of said data structure.

3. An apparatus according to claim 1, wherein said adjusting means includes means for contracting a size of said data structure.

4. An apparatus according to claim 1, wherein said data structure includes at least one data object and a directory comprising at least one directory element respectively locating said at least one data object, wherein said adjusting means includes means for altering a relative number of said at least one directory entry and said at least one data object of said data structure.

5. An apparatus according to claim 1, wherein said data structure includes at least one data object and a directory comprising at least one directory element respectively locating said at least one data object, wherein said adjusting means includes means for expanding a size of said data structure and means for altering a relative number of said at least one directory entry and said at least one data object of said data structure.

6. An apparatus according to claim 1, wherein said data structure includes at least one data object and a directory comprising at least one directory element respectively locating said at least one data object, wherein said adjusting means includes means for contracting a size of said data structure and means for altering a relative number of said at least one directory entry and said at least one data object of said data structure.

7. An apparatus according to claim 1, further comprising means for measuring progress of execution of said second allocation parameters.

8. An apparatus according to claim 7, further comprising means for terminating progress of said second allocation parameters based on an input from said measuring means.

9. An apparatus according to claim 8, further comprising means for altering said second allocation parameters based on said input from said measuring means.

10. A method of optimizing a data structure of an external data storage facility shared by a plurality of data processing systems, said data structure being allocated by a first allocation command which includes first allocation parameters based on an amount of storage space in said external data storage facility assigned for creation of said data structure and a composition of said data structure, said method comprising the steps of:

determining values of said first allocation parameters, to thereby determine a first composition of said data structure;

determining an actual usage of said data structure, to thereby determine a second composition of said data structure;

comparing said first composition of said data structure with said second composition of said data structure to provide a comparison output;

issuing, responsive to said comparison output, a second allocation command having second allocation parameters, to said data structure for reallocation thereof,

adjusting said first composition of said data structure to said second composition, as storage space in said external data storage facility and processing cycles become available to execute said second allocation parameters,

wherein, until said second allocation parameters are achieved, the reallocation of said data structure remains pending and all processing commands are accepted and processed by said external data storage facility.

11. A method according to claim 10, wherein said step of adjusting includes a step of expanding a size of said data structure.

12. A method according to claim 10, wherein said step of adjusting includes a step of contracting a size of said data structure.

13. A method according to claim 10, wherein said data structure includes at least one data object and a directory comprising at least one directory element respectively locating said at least one data object, wherein said step of adjusting includes a step of altering a relative number of said at least one directory entry and said at least one data object of said data structure.

14. A method according to claim 10, wherein said data structure includes at least one data object and a directory comprising at least one directory element respectively locating said at least one data object, wherein said step of adjusting includes a step of expanding a size of said data structure and a step of altering a relative number of said at least one directory entry and said at least one data object of said data structure.

15. A method according to claim 10, wherein said data structure includes at least one data object and a directory comprising at least one directory element respectively locating said at least one data object, wherein said step of adjusting includes a step of contracting a size of said data structure and a step of altering a relative number of said at least one directory entry and said at least one data object of said data structure.

16. A method according to claim 10, further comprising a step of measuring progress of execution of said second allocation parameters.

17. A method according to claim 16, further comprising a step of terminating progress of said second allocation parameters based on said step of measuring.

18. A method according to claim 17, further comprising a step of altering said second allocation parameters based on said step of measuring.

19. A method according to claim 11, wherein said step of expanding a size of said structure includes:

a step of determining when continuing said step of expanding would cause a relative number of said at least one directory entry and said at least one data object to change, and

a step of terminating said step of expanding when it is determined that continuing said step of expanding would cause said relative number of said at least one directory entry and said at least one data object to change.

20. A method according to claim 12, wherein said step of contracting a size of said structure includes:

a step of determining when continuing said step of contracting would cause a relative number of said at least one directory entry and said at least one data object to change, and

a step of terminating said step of contracting 8 when it is determined that continuing said step of expanding would cause said relative number of said at least one directory entry and said at least one data object to change.

21. A method according to claim 12, wherein said step of contracting a size of said structure includes:

a step of determining when continuing said step of contracting would cause a number of said at least one directory entry to decrease below a predetermined amount, and

a step of terminating said step of contracting when it is determined that continuing said step of expanding would cause said number of said at least one directory entry to become less than said predetermined amount.

22. A method according to claim 12, wherein said step of contracting a size of said structure includes:

a step of determining when continuing said step of contracting would cause a number of said at least one data object to decrease below a predetermined amount, and

a step of terminating said step of contracting when it is determined that continuing said step of expanding would cause said number of said at least one data object to become less than said predetermined amount.