Method for moving an open file being accessed by at least one user

• US 5,655,119 A
• Filed: 02/12/1996
• Issued: 08/05/1997
• Est. Priority Date: 12/07/1992
• Status: Expired due to Term

• Current Assignee: Raxco Software Incorporated
• Original Assignee: AXENT Technologies, Inc. (Gen Digital Inc.)
• Inventors: Davy, William R.
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): Von Buhr, Maria N.
• Application Number:
  US08/600,080
• Time in Patent Office: 540 Days
• Field of Search: 364/DIG. 1, 364/DIG. 2, 395/425, 395/600, 395/616
• US Class Current: 1/1
• CPC Class Codes: G06F 16/1724 Details of de-fragmentation performed by the file system saving storage space on storage systems G06F3/0608; management of blocks in storage devices G06F3/064

Abstract

A method for moving open files on a computer system is disclosed. According to one aspect of the invention, an open file may be accessed by a user while being moved. To ensure accuracy, if data is to be written to an open file while it is being moved, the data is written to both the old and new locations.

Claims

1. A method for moving an open file in a computer system, wherein said open file is currently being accessed by at least one user, said method comprising the steps of:

identifying an open file which is located at a first portion of a disk, where at least a portion of said file is to be moved to a second portion of said disk;

moving at least a portion of said open file to said second portion of said disk, said moving step comprising the steps of;

(a) copying said portion of said open file to said second portion of said disk;

(b) updating said open file at said first portion of said disk and said copied portion at said second portion of said disk in response to a request to write to said open file received after completion of said identifying step; and

,

(c) deallocating said first portion of said disk after completion of said copying step.

2. The method of claim 1 further comprising the step of acquiring and maintaining a lock on said open file while said open file is being moved to said second portion of said disk wherein said lock prevents said user from extending or truncating said open file while said lock is maintained on said open file.

3. The method of claim 2 wherein said access by at least one user comprises a request for reading or writing data and wherein said access by at least one user further comprises a first set of user access requests which are initiated prior to completion of said identifying step and a second set of user access requests which are initiated after completion of said identifying step and prior to initiation of said moving step and further comprising the steps of:

queuing said second set of user access requests after completion of said identifying step until initiation of said moving step;

executing said first set of user access requests;

initiating said moving step; and

executing said second set of user access requests from said queue after said initiating step.

4. The method of claim 3 wherein said access by at least one user further comprises a third set of user access requests which are initiated during said moving step and further comprising the steps of:

executing said third set of user access requests after completion of said moving step and said step of executing said second set of user access requests; and

releasing said lock.

5. The method of claim 4 wherein said open file comprises header information associated therewith and wherein said header information includes information identifying at least a location of said first portion and further comprising the steps of:

updating said header information associated with said open file before said releasing step and after said moving step; and

writing data for said open file to only said second portion of said disk after completion of said updating step until said releasing step has been completed.

6. The method of claim 1 wherein once said step of updating said first and second portions of said disk begins, no portion of the open file is copied until said data is written to both said first and second portions of said disk.

7. The method of claim 1 wherein said copying step comprises a plurality of read/write sequences and wherein said updating step occurs subsequent to one of said read/write sequences.

8. In a computer system comprising one or more disks, said system comprising means for defragmenting files by moving at least a portion of said files and by moving file positions on at least one of said disks, a method for moving at least a portion of an open file while said file is being accessed by a user, said method comprising the steps of:

determining a portion of said file to be moved from a first location to a second location;

copying said portion of said file to said second location while enabling said file to continue to be accessed by said user; and

,

deallocating said first location after said copying step has been completed;

wherein when a user request to write data to said file during said step of copying is made, said data is written to said file by writing said data to both said first and second locations.

9. The method of claim 8 wherein said copying step comprises a plurality of read/write sequences and wherein said writing step occurs subsequent to one of said read/write sequences.

10. The method of claim 8 wherein said access by a user comprises a request for reading or writing data.

11. The method of claim 10 further comprising the step of acquiring and maintaining a lock on said open file while said open file is being moved to said second location wherein said lock prevents said user from extending or truncating said open file while said lock is maintained on said open file.

12. The method of claim 11 wherein said access by a user further comprises a first set of user access requests which are initiated prior to completion of said determining step and a second set of user access requests which are initiated after completion of said determining step and prior to initiation of said copying step and further comprising the steps of:

queuing said second set of user access requests after completion of said determining step until initiation of said copying step;

executing said first set of user access requests;

initiating said copying step; and

executing said second set of user access requests from said queue after said initiating step.

13. The method of claim 12 wherein said access by a user further comprises a third set of user access requests which are initiated during said copying step and further comprising the steps of:

executing said third set of user access requests after completion of said copying step and said step of executing said second set of user requests; and

releasing said lock.

14. The method of claim 13 wherein said open file comprises header information associated therewith and wherein said header information includes information identifying at least said first location and further comprising the steps of:

updating said header information associated with said open file before said releasing step and after said copying step; and

writing data for said open file to only said second location of said disk after completion of said updating step until said releasing step has been completed.

15. A method of moving at least a portion of a file in a computer system, including files being accessed by at least one user, said method comprising the steps of:

identifying at least a portion of a file to be moved, said portion comprising at least one file segment located at a first disk portion and a file header pointing to said first disk portion, wherein said file segment is to be moved to a second disk portion;

determining if said identified portion is being accessed by at least one user, and if so, moving said portion of said file by executing a method for moving open files, said method for moving open files comprising the steps of;

copying said file segment to said second disk portion;

updating said file to be moved at said first disk portion and said second disk portion in response to a request to write to said file received after completion of said identifying step;

rewriting said file header to point to said second disk portion; and

deallocating said first disk portion.

16. The method of claim 15 wherein the access by at least one user comprises requests for reading and writing to said identified portion, said requests comprising a first set of user access requests which are initiated prior to completion of said determining step, a second set of user access requests which are initiated after completion of said determining step and prior to initiation of said copying step and a third set of user access requests which are initiated after initiation of said copying step, and further comprising the steps of:

queuing said first set of user access requests until completion of said determining step;

acquiring and maintaining an open file extension/truncation lock on said identified portion after said determining step;

queuing said second set of user access requests after completion of said determining step until initiation of said copying step;

executing said first set of user access requests;

initiating said copying step;

queuing said third set of user access requests after initiation of said copying step;

executing said second set of user access requests from said queue after said initiating step; and

executing said third set of user access requests after completion of said copying step and after said step of executing said second set of user access requests;

wherein said user access requests of said second and third sets which involve write operations are performed on the identified portion and the copied file; and

,

wherein said user access requests of said second and third sets which involve read operations are performed on the identified portion.