Point-in-time recovery on deduplicated storage

• US 10,255,137 B1
• Filed: 12/16/2013
• Issued: 04/09/2019
• Est. Priority Date: 12/16/2013
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Inventors: Panidis, Anestis, Natanzon, Assaf, Cohen, Saar
• Primary Examiner(s): Talukdar, Arvind
• Application Number:
  US14/108,032
• Time in Patent Office: 1,940 Days
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 11/1453 using de-duplication of the data
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery

Abstract

Method and system for point-in-time recovery from a deduplicated data system is discussed. A request specifying a point-in-time may be received. A backup snapshot nearest that point-in-time may be identified, and a recovery snapshot may be synthesized.

Claims

1. A method for point-in-time recovery on deduplicated storage, the method comprising:

receiving a request to recover data, the request specifying a point-in-time;

defining data protection windows wherein a first data protection window protects snapshots and journal entries and has a first defined protection time range, a second data protection window has a second defined protection time range, and a third data protection window has a third defined protection time range, wherein each defined protection time range represents a backup granularity designating how long a stored snapshot or journal entry is to be stored in each respective data protection window;

moving snapshots and journal entries from the first data protection window to the second data protection window, and moving snapshots from the second data protection to the third data protection window as time progresses;

defining respective policies to each data protection window to delete journal entries from the second data protection window after movement from the first data protection window so that only snapshots are stored in the second and third data protection windows, and to delete certain snapshots from the second data protection window so that only prioritized snapshots are stored in the third data protection window;

dynamically changing each of the first, second, and third data protection window time ranges based on available space in the deduplicated storage to optimize a retention time for protected snapshots and journal entries of the first data protection window if the available space is large or to optimize a retention time for the prioritized snapshots of the third data protection window if the available space is small;

identifying a backup snapshot nearest to the point-in-time, wherein the backup snapshot has a defined backup granularity defined by the respective data protection window storing the backup snapshot;

identifying a journal entry nearest to the point-in-time, wherein the journal entry is within a journal;

synthesizing a recovery snapshot from the backup snapshot and the journal entry;

providing the recovery snapshot in response to the request, wherein providing the recovery snapshot comprises exposing the recovery snapshot as a logical unit (“

LU”

);

mounting the LU on a host device;

receiving IOs for the LU from the host device;

applying the IOs to the recovery snapshot to create a modified recovery snapshot;

identifying a difference between the backup snapshot and the modified recovery snapshot, the difference comprising metadata journal entries associated with the IOs

adding the metadata journal entries to a recovery list; and

transmitting data associated with the metadata entries to a source storage system.

2. The method of claim 1, wherein synthesizing the recovery snapshot comprises applying DO IOs when the backup snapshot was taken earlier than the point-in-time.

3. The method of claim 1, wherein the point-in-time exists between existing snapshots, and wherein the first defined protection time range comprises a short-term protection window, the second defined protection time range comprises a mid-term protection window, and the third defined protection time range comprises a long-term protection window.

4. The method of claim 3, wherein each data protection window of the one or more data protection windows has an associated policy specifying actions to take on any backup snapshot or journal entry in a respective data protection window, and wherein a first associated policy specifies that only certain periodic journal entries be deleted from the first data protection window and a second associated policy specifies that only certain periodic snapshots be retained in the third data protection window.

5. The method of claim 1, further comprising transmitting the difference to a recovery device in response to the request.

6. The method of claim 1, wherein providing the recovery snapshot comprises transmitting the recovery snapshot to a recovery device.

7. The method of claim 4, wherein the backup snapshot nearest to the point-in-time is stored in a short-term protection window.

8. A computer program product for point-in-time recovery on deduplicated storage, the computer program product comprising a non-transitory computer readable medium encoded with computer executable program, the code enabling:

receiving a request to recover data, the request specifying a point-in-time;

defining data protection windows wherein a first data protection window protects snapshots and journal entries and has a first defined protection time range, a second data protection window has a second defined protection time range, and a third data protection window has a third defined protection time range, wherein each defined protection time range represents a backup granularity designating how long a stored snapshot or journal entry is to be stored in each respective data protection window;

moving snapshots and journal entries from the first data protection window to the second data protection window, and moving snapshots from the second data protection to the third data protection window as time progresses;

defining respective policies to each data protection window to delete journal entries from the second data protection window after movement from the first data protection window so that only snapshots are stored in the second and third data protection windows, and to delete certain snapshots from the second data protection window so that only prioritized snapshots are stored in the third data protection window;

dynamically changing each of the first, second, and third data protection window time ranges based on available space in the deduplicated storage to optimize a retention time for protected snapshots and journal entries of the first data protection window if the available space is large or to optimize a retention time for the prioritized snapshots of the third data protection window if the available space is small;

identifying a backup snapshot nearest to the point-in-time, wherein the backup snapshot has a defined backup granularity defined by the respective data protection window storing the backup snapshot;

identifying a journal entry nearest to the point-in-time, wherein the journal entry is within a journal;

synthesizing a recovery snapshot from the backup snapshot and the journal entry;

providing the recovery snapshot in response to the request, wherein providing the recovery snapshot comprises exposing the recovery snapshot as a logical unit (“

LU”

);

mounting the LU on a host device;

receiving IOs for the LU from the host device;

applying the IOs to the recovery snapshot to create a modified recovery snapshot;

identifying a difference between the backup snapshot and the modified recovery snapshot, the difference comprising metadata journal entries associated with the IOs

adding the metadata journal entries to a recovery list; and

transmitting data associated with the metadata entries to a source storage system.

9. The computer program product of claim 8, wherein the point-in-time exists between existing snapshots, and wherein the first defined protection time range comprises a short-term protection window, the second defined protection time range comprises a mid-term protection window, and the third defined protection time range comprises a long-term protection window.

10. The computer program product of claim 9, wherein each data protection window of the one or more data protection windows has an associated policy specifying actions to take on any backup snapshot or journal entry in a respective data protection window, and wherein a first associated policy specifies that only certain periodic journal entries be deleted from the first data protection window and a second associated policy specifies that only certain periodic snapshots be retained in the third data protection window.

11. The computer program product of claim 10, wherein providing the recovery snapshot comprises exposing the recovery snapshot as a logical unit (“

LU”

), wherein the backup snapshot nearest to the point-in-time is stored in a short-term protection window, and wherein, as time progresses, snapshots and journal entries move from the short-term protection window to the long-term protection window through the medium term protection window, and wherein a policy of a final protection window is applied to a moved snapshot or journal entry.

12. A system for point-in-time recovery on deduplicated storage, the system comprising a computer processor configured to execute instructions comprising:

receiving a request to recover data, the request specifying a point-in-time;

defining data protection windows wherein a first data protection window protects snapshots and journal entries and has a first defined protection time range, a second data protection window has a second defined protection time range, and a third data protection window has a third defined protection time range, wherein each defined protection time range represents a backup granularity designating how long a stored snapshot or journal entry is to be stored in each respective data protection window;

moving snapshots and journal entries from the first data protection window to the second data protection window, and moving snapshots from the second data protection to the third data protection window as time progresses;

defining respective policies to each data protection window to delete journal entries from the second data protection window after movement from the first data protection window so that only snapshots are stored in the second and third data protection windows, and to delete certain snapshots from the second data protection window so that only prioritized snapshots are stored in the third data protection window;

dynamically changing each of the first, second, and third data protection window time ranges based on available space in the deduplicated storage to optimize a retention time for protected snapshots and journal entries of the first data protection window if the available space is large or to optimize a retention time for the prioritized snapshots of the third data protection window if the available space is small;

identifying a backup snapshot nearest to the point-in-time, wherein the backup snapshot has a defined backup granularity defined by the respective data protection window storing the backup snapshot;

identifying a journal entry nearest to the point-in-time, wherein the journal entry is within a journal;

synthesizing a recovery snapshot from the backup snapshot and the journal entry;

providing the recovery snapshot in response to the request, wherein providing the recovery snapshot comprises exposing the recovery snapshot as a logical unit (“

LU”

);

mounting the LU on a host device;

receiving IOs for the LU from the host device;

applying the IOs to the recovery snapshot to create a modified recovery snapshot;

identifying a difference between the backup snapshot and the modified recovery snapshot, the difference comprising metadata journal entries associated with the IOs

adding the metadata journal entries to a recovery list; and

transmitting data associated with the metadata entries to a source storage system.

13. The system of claim 12, wherein the point-in-time exists between existing snapshots, and wherein the first defined protection time range comprises a short-term protection window, the second defined protection time range comprises a mid-term protection window, and the third defined protection time range comprises a long-term protection window.

14. The system of claim 13, wherein each data protection window of the one or more data protection windows has an associated policy specifying actions to take on any backup snapshot or journal entry in a respective data protection window.

15. The system of claim 14, wherein the backup snapshot nearest to the point-in-time is stored in a short-term protection window, and wherein, as time progresses, snapshots and journal entries move from the short-term protection window to the long-term protection window through the medium term protection window, and wherein a policy of a final protection window is applied to a moved snapshot or journal entry.