Recovering corrupt virtual machine disks

• US 9,588,847 B1
• Filed: 03/25/2014
• Issued: 03/07/2017
• Est. Priority Date: 03/25/2014
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Inventors: Natanzon, Assaf, Cohen, Saar, Panidis, Anestis
• Primary Examiner(s): Beausoliel, Jr., Robert
• Assistant Examiner(s): Hoang, Hau H
• Application Number:
  US14/225,089
• Time in Patent Office: 1,078 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1453 using de-duplication of the data
• CPC Class Codes: G06F 11/1458 Management of the backup or restore process
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• CPC Class Codes: G06F 11/2097 maintaining the standby controller/processing unit updated initialisation or re-synchronisation thereof G06F11/1658 and subgroups
• 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 16/27 Replication, distribution or synchronisation of data between databases or within a distributed database system; Distributed database system architectures therefor
• CPC Class Codes: G06F 2201/815 Virtual
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

A method and system for recovering a corrupt virtual disk is discussed. A request to recover the disk may be received. A recovery snapshot for the last point-in-time the system was stable may be synthesized. A difference may be identified between that recovery snapshot and the corrupt disk. A virtual machine may communicate with both the difference and the corrupt disk, and the difference may be merged with the corrupt disk.

Claims

1. A method for recovering a virtual machine, the method comprising:

receiving a request to recover a corrupt virtual disk, the request comprising a point-in-time;

producing a recovery snapshot for the point-in-time;

identifying a difference between the recovery snapshot and a backup snapshot at a deduplicated storage;

adding the difference to a difference list that comprises pointers to difference data, the difference data comprising data that is different between the corrupt virtual disk and the recovery snapshot;

identifying an input/output (“

IO”

) in a recovery system memory;

adding the IO to the difference list;

identifying a journal entry entered after the backup snapshot was synthesized,

wherein the journal entry includes a record of write transactions;

adding the journal entry to the difference list;

synthesizing a difference snapshot from the difference list; and

exposing the difference snapshot to the virtual machine.

2. The method of claim 1, wherein producing the recovery snapshot comprises synthesizing a new snapshot from a backup snapshot and a journal.

3. The method of claim 1, wherein the recovery snapshot is a backup snapshot.

4. The method of claim 1, wherein exposing the difference snapshot comprises reconfiguring the virtual machine to use the corrupt virtual disk with the difference snapshot.

5. The method of claim 1, further comprising receiving writes to the difference snapshot from the virtual machine.

6. The method of claim 1, further comprising receiving read requests for the difference from the virtual machine.

7. The method of claim 1, further comprising receiving a merge request.

8. The method of claim 7, further comprising transmitting data associated with the difference snapshot to a primary storage in response to the merge request.

9. The method of claim 8, further comprising merging the data with the corrupt virtual disk.

10. A computer program product for recovering a virtual machine, the computer program product comprising a non-transitory computer readable medium encoded with computer executable program, the code enabling:

receiving a request to recover a corrupt virtual disk, the request comprising a point-in-time;

producing a recovery snapshot for the point-in-time;

identifying a difference between the recovery snapshot and a backup snapshot at a deduplicated storage;

adding the difference to a difference list;

identifying an input/output (“

IO”

) in a recovery system memory;

adding the IO to the difference list that comprises pointers to difference data, the difference data comprising data that is different between the corrupt virtual disk and the recovery snapshot;

identifying a journal entry entered after the backup snapshot was synthesized,

wherein the journal entry includes a record of write transactions;

adding the journal entry to the difference list;

synthesizing a difference snapshot from the difference list; and

exposing the difference snapshot to the virtual machine.

11. The computer program product of claim 10,

wherein the difference list comprises pointers to difference data, the difference data comprising data that is different between the corrupt virtual disk and the recovery snapshot.

12. A system for recovering a virtual machine, the system comprising a computer processor configured to execute instructions comprising:

receiving a request to recover a corrupt virtual disk, the request comprising a point-in-time;

producing a recovery snapshot for the point-in-time;

identifying a difference between the recovery snapshot and a backup snapshot at a deduplicated storage;

adding the difference to a difference list;

identifying an input/output (“

IO”

) in a recovery system memory;

adding the IO to the difference list that comprises pointers to difference data, the difference data comprising data that is different between the corrupt virtual disk and the recovery snapshot;

identifying a journal entry entered after the backup snapshot was synthesized,

wherein the journal entry includes a record of write transactions;

adding the journal entry to the difference list;

synthesizing a difference snapshot from the difference list; and

exposing the difference snapshot to the virtual machine.

13. The system of claim 12, wherein the difference list comprises pointers to difference data, the difference data comprising data that is different between the corrupt virtual disk and the recovery snapshot.