Method and apparatus for implementing a highly efficient, robust modified files list (MFL) for a storage system volume

• US 6,560,615 B1
• Filed: 12/17/1999
• Issued: 05/06/2003
• Est. Priority Date: 12/17/1999
• Status: Expired due to Term

• Current Assignee: Micro Focus Software, Inc. (Open Text Corporation)
• Original Assignee: Novell Incorporated (Open Text Corporation)
• Inventors: Susarla, Sai Rama Krishna, Zayas, Edward R.
• Primary Examiner(s): Metjahic, Safet
• Assistant Examiner(s): ALAUBAIDI, HAYTHIM J
• Application Number:
  US09/466,359
• Time in Patent Office: 1,236 Days
• Field of Search: 707/202, 707/204, 707/200, 707/104.1, 707/203
• US Class Current: 707/646
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

When a volume is created, a Modified Files List (MFL) is established and an epoch timestamp, identifying an important point in time, is set for the volume. Entries are inserted into the MFL whenever files are first added to or changed on the volume. Entries are flagged with the epoch timestamp in which they are added to the MFL. Entries are removed from the MFL when files are restored to an already-archived condition or are deleted from the volume. A system administrator can declare a new epoch at any time, and will declare a new epoch before performing a backup. The system administrator will select an epoch for backup purposes. The files inserted into the MFL before the selected epoch timestamp are enumerated and archived using a backup tool. After the backup tool turns off a file'"'"'s data and metadata archive bits, the corresponding entry is removed from the MFL.

Claims

1. A method for using a modified files list to store a list of files, each file including data and metadata bits, to back up on a volume stored on a storage medium on a computer system, the method comprising:

establishing an epoch timestamp in a volume;

organizing the modified files list as a B+ tree;

updating the modified files list as a file is added to, removed from, or changed on the volume;

selecting a way-point epoch timestamp; and

using a backup tool to archive all files listed in the modified files list which were added to the modified files list before the way-point epoch timestamp.

2. A method according to claim 1 further comprising replacing the established epoch timestamp with a new epoch timestamp.

3. A method according to claim 1 wherein updating the modified files list includes inserting an entry to the modified files list whenever the file'"'"'s data or metadata bits are turned on.

4. A method according to claim 3 wherein updating the modified files list further includes storing the established epoch timestamp in the modified files list for the file added to or changed on the volume.

5. A method according to claim 1 wherein updating the modified files list includes deleting an entry from the modified files list whenever the file'"'"'s data and metadata bits are turned off.

6. A method according to claim 1 further comprising enumerating the files in the modified files list which were added to the modified files list before the way-point epoch timestamp was selected.

7. A method according to claim 6 wherein enumerating the files in the modified files list includes ordering the enumerated files.

8. A method according to claim 1 wherein using a backup tool includes deleting an entry from the modified files list after the backup tool turns off the file'"'"'s data and metadata bits.

9. A computer-readable medium containing a program implementing an algorithm for using a modified files list to store a list of files, each file including data and metadata bits, to back up on a volume'"'"'stored on a storage medium on a computer system, the program comprising:

timestamp software to establish an epoch timestamp in a volume;

organizational software to organize the modified files list as a B+ tree;

update software to update the modified files list whenever a file is added to, removed from, or changed on the volume;

selection software to select a way-point epoch timestamp; and

backup software to archive all files listed in the modified files list which were added to the modified files list before the way-point epoch timestamp was selected.

10. A computer-readable medium containing a program according to claim 9 wherein the update software to update the modified files list includes insertion software to insert an entry to the modified files list whenever the file'"'"'s data or metadata bits are turned on.

11. A computer-readable medium containing a program according to claim 9 wherein the update software to update the modified files list includes deletion software to delete an entry from the modified files list whenever the file'"'"'s data and metadata bits are turned off.

12. A computer-readable medium containing a program according to claim 9 further comprising enumeration software to enumerate the files in the modified files list which were added to the modified files list before the way-point epoch timestamp was selected.

13. A computer-readable medium containing a program according to claim 12 wherein the enumeration software to enumerate the files in the modified files list includes ordering software to order the enumerated files.

14. A computer-readable medium containing a program according to claim 9 wherein the backup software includes deletion software to delete an entry from the modified files list after the backup tool turns off the file'"'"'s data and metadata bits.

15. An apparatus for using a modified files list to store a list of files to back up on a volume stored on a storage medium on a computer system, the apparatus comprising:

a modified files list, wherein the modified files list includes data structures identifying a list of files that have been changed since they were last backed up and the modified files list is organized as a B+ tree;

a way-point epoch timestamp in the volume;

an operating system running on the computer system, wherein the operating system is organized to update the modified files list when a file is added to, removed from, or changed on the volume to reflect the way-point epoch timestamp; and

a backup tool to archive files stored in the modified files list which were added to the modified files list before the way-point epoch timestamp.

16. An apparatus according to claim 15, wherein each data structure includes:

a file identifier; and

the epoch timestamp.

17. An apparatus for using a modified files list to store a list of files, each file including data and metadata bits, to back up on a volume stored on a storage medium on a computer system, the modified files list organized as a B+ tree and the apparatus comprising:

a timestamp unit to establish an epoch timestamp in a volume;

an update unit to update the modified files list whenever a file is added to, removed from, or changed on the volume;

a selection unit to select a way-point epoch timestamp; and

backup tool to archive all files listed in the modified files list which were added to the modified files list before the way-point epoch timestamp was selected.

18. An apparatus according to claim 17 wherein the update unit to update the modified files list includes an insertion unit to insert an entry to the modified files list whenever the file'"'"'s data or metadata bits are turned on.

19. An apparatus according to claim 17 wherein the update unit to update the modified files list includes a deletion unit to delete an entry from the modified files list whenever the file'"'"'s data and metadata bits are turned off.

20. An apparatus according to claim 17 further comprising:

an enumeration unit to enumerate the files in the modified files list which were added to the modified files list before the way-point epoch stamp; and

an ordering unit to order the enumerated files.