Copy on write storage conservation systems and methods

• US 9,015,430 B2
• Filed: 03/02/2010
• Issued: 04/21/2015
• Est. Priority Date: 03/02/2010
• Status: Expired due to Fees

• Current Assignee: Veritas Technologies, LLC (Whitehouse Group Ltd.)
• Original Assignee: Symantec Corporation (NortonLifeLock Inc.)
• Inventors: Ranade, Dilip Madhusudan
• Primary Examiner(s): Choe, Yong
• Assistant Examiner(s): Waddy, Jr., Edward
• Application Number:
  US12/716,201
• Publication Number:
  US 20110219201A1
• Time in Patent Office: 1,876 Days
• Field of Search: 711/162, 711/E12.103, 711/171, 707/649, 707/639, 707/657, 707/999.204
• US Class Current: 711/162
• CPC Class Codes: G06F 16/128 Details of file system snapshots on the file-level, e.g. snapshot creation, administration, deletion use of snapshots for error detection or correction G06F11/14, G06F11/16
• CPC Class Codes: G06F 16/1727 Details of free space management performed by the file system saving storage space on storage systems G06F3/0608; management of blocks in storage devices G06F3/064
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

Systems and methods for copy on write storage conservation are presented. In one embodiment a copy on write storage conservation method includes creating and mounting a snapshot; mounting a snapshot; monitoring interest in the snapshot; initiating a copy on write discard process before a backup or replication is complete; and deleting the snapshot when the backup or replication is complete. In one embodiment the method also includes marking a file as do not copy on write. In one embodiment, the copy on write discard process includes discarding copy on write data when a corresponding read on the file in the snapshot is successful. Initiating a copy on write discard process can be done at a variety of levels (e.g., a file level, an extent level, a block-level, etc.).

Claims

1. A copy on write storage conservation method comprising:

creating and mounting a snapshot;

monitoring interest in the snapshot, including determining that a backup or replication process has read copy on write data and is no longer interested in the copy on write data, wherein the determining is based at least in part on a pattern of reading file data including the copy on write data;

initiating a copy on write discard process before the backup or replication process is complete; and

un-mounting and deleting the snapshot when the backup or replication process is complete.

2. The method of claim 1 further comprising marking a file as do not copy on write.

3. The method of claim 1 wherein the copy on write discard process includes discarding copy on write data associated with a block when a corresponding read on the block is successful.

4. The method of claim 1, wherein the copy on write discard process includes a signal to delete copy on write blocks, and wherein the signal is associated with a function of a file indicating reads of information from the file are finished.

5. The method of claim 1 wherein the copy on write discard process includes:

determining that backup or replication applications read file data in peculiar patterns; and

deleting copy on write data for a particular file when it is safe in accordance with the peculiar pattern.

6. The method of claim 1 wherein initiating a copy on write discard process is done at a file level, block level and extent level.

7. The method of claim 1 wherein a public application program interface is configured to set the snapshot in an aggressive de-allocation mode initiated before the completion of the backup or replication process.

8. A non-transitory computer readable storage medium having stored thereon computer-executable instructions that, when executed by a computing device, cause the computing device to perform a copy on write storage conservation method comprising:

creating and mounting a snapshot;

monitoring interest in the snapshot, including determining that a backup or replication process has read copy on write data and is no longer interested in the copy on write data, wherein the determining is based at least in part on a pattern of reading file data including the copy on write data;

initiating a copy on write discard process before the backup or replication process is complete; and

un-mounting and deleting the snapshot when the backup or replication process is complete.

9. The non-transitory computer readable storage medium of claim 8 further comprising marking a file as do not copy on write.

10. The non-transitory computer readable storage medium of claim 8 wherein the copy on write discard process includes discarding copy on write data associated with a block when a corresponding read on the block is successful.

11. The non-transitory computer readable storage medium of claim 8, wherein the copy on write discard process includes a signal to delete copy on write blocks, and wherein the signal is associated with a function of the file indicating reads of information from the file are finished.

12. The non-transitory computer readable storage medium of claim 8 wherein the copy on write discard process includes:

determining that backup or replication applications read file data in peculiar patterns; and

discarding the copy on write data for a particular file when it is safe in accordance with the peculiar pattern.

13. The non-transitory computer readable storage medium of claim 8 wherein initiating a copy on write discard process is done at a file level, block level and extent level.

14. The non-transitory computer readable storage medium of claim 8 wherein a public application program interface is configured to set the snapshot in an aggressive de-allocation mode initiated before the completion of the backup or replication process.

15. A system, comprising:

a computer system having a computer processor coupled to non-transitory computer readable storage media and executing computer readable code which causes the computer system to perform a copy on write storage conservation method comprising;

creating and mounting a snapshot;

monitoring interest in the snapshot, including determining that a backup or replication process has read copy on write data and is no longer interested in the copy on write data, wherein the determining is based at least in part on a pattern of reading file data including the copy on write data;

initiating a copy on write discard process before the backup or replication process is complete; and

un-mounting and deleting the snapshot when the backup or replication process is complete.

16. The system of claim 15 further comprising marking a file as do not copy on write.

17. The system of claim 15 wherein the copy on write discard process includes discarding copy on write data associated with a block when a corresponding read on the block is successful.

18. The system of claim 15, wherein the copy on write discard process includes a signal to delete copy on write blocks, and wherein the signal is associated with a function of the file indicating reads of information from the file are finished.

19. The system of claim 15 wherein the copy on write discard process includes:

determining that backup or replication applications read file data in peculiar patterns; and

discarding the copy on write data for a particular file when it is safe in accordance with the peculiar pattern.

20. The system of claim 15 wherein initiating a copy on write discard process is done in at a file level, block level and extent level.