Recovering corrupt storage systems

• US 9,875,162 B1
• Filed: 12/16/2013
• Issued: 01/23/2018
• Est. Priority Date: 12/16/2013
• Status: Active Grant

• Current Assignee: EMC Corporation (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Panidis, Anestis, Natanzon, Assaf, Cohen, Saar
• Primary Examiner(s): Trujillo, James
• Assistant Examiner(s): Khoshnoodi, Fariborz
• Application Number:
  US14/108,072
• Time in Patent Office: 1,499 Days
• Field of Search: 707639, 707640
• CPC Class Codes: G06F 11/1453 using de-duplication of the data
• CPC Class Codes: G06F 11/1464 for networked environments
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• 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 16/1748 De-duplication implemented within the file system, e.g. based on file segments de-duplication techniques in storage systems for the management of data blocks G06F3/0641
• CPC Class Codes: G06F 16/2308 Concurrency control transaction processing G06F9/466
• 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 storage system is discussed. A request to recover the system may be received. A backup snapshot for the last point-in-time the system was stable may be synthesized. A difference may be identified between that backup snapshot and the current system. The difference may be transmitted to the corrupt system to recover the data.

Claims

1. A method for recovering a source storage system, the method comprising:

intercepting write transactions issued by a host computer to the source storage system before the write transactions are received at the source storage system;

streaming the intercepted write transactions to a backup storage system;

upon receipt of the stream of intercepted write transactions at the backup storage system, recording metadata associated with the write transactions in a metadata journal at the backup storage system, and data associated with the write transactions in a data journal at the backup storage system;

after the recording metadata and data, allowing the write transactions issued by the host computer to be received at the source storage system;

periodically synthesizing backup snapshots of the source storage system using the metadata journal and data journal at the backup storage system;

receiving a request to recover data for the source storage system, the request comprising a point-in-time that is before a logical corruption of the source storage system;

synthesizing a recovery snapshot for the point-in-time using the metadata journal and data journal at the backup storage system;

identifying a difference between the recovery snapshot and a latest synthesized backup snapshot, the latest synthesized backup snapshot having been created for a point-in-time that is after the point-in-time of the recovery snapshot;

adding the difference to a recovery list as entries in the recovery list;

identifying metadata entries in the metadata journal at the backup storage system, wherein the metadata entries are not in the latest synthesized backup snapshot;

adding the metadata entries to the recovery list; and

transmitting data associated with entries in the recovery list to the source storage system.

2. The method of claim 1, further comprising:

identifying additional metadata entries in a data protection appliance memory at the backup storage system, wherein the additional metadata entries have not been written to the metadata journal; and

adding the additional metadata entries to the recovery list.

3. A computer program product for recovering a source storage system, the computer program product comprising a non-transitory computer readable medium encoded with computer executable program, the code enabling:

intercepting write transactions issued by a host computer to the source storage system before the write transactions are received at the source storage system;

streaming the intercepted write transactions to a backup storage system;

upon receipt of the stream of intercepted write transactions at the backup storage system, recording metadata associated with the write transactions in a metadata journal at the backup storage system, and data associated with the write transactions in a data journal at the backup storage system;

after the recording metadata and data, allowing the write transactions issued by the host computer to be received at the source storage system;

periodically synthesizing backup snapshots of the source storage system using the metadata journal and data journal at the backup storage system;

receiving a request to recover data for the source storage system, the request comprising a point-in-time that is before a logical corruption of the source storage system;

synthesizing a recovery snapshot for the point-in-time using the metadata journal and data journal at the backup storage system;

identifying a difference between the recovery snapshot and a latest synthesized backup snapshot, the latest synthesized backup snapshot having been created for a point-in-time that is after the point-in-time of the recovery snapshot;

adding the difference to a recovery list as entries in the recovery list;

identifying metadata entries in the metadata journal at the backup storage system, wherein the metadata entries are not in the latest synthesized backup snapshot;

adding the metadata entries to the recovery list; and

transmitting data associated with entries in the recovery list to the source storage system.

4. The computer program product of claim 3, further comprising:

identifying additional metadata entries in a data protection appliance memory at the backup storage system, wherein the additional metadata entries have not been written to the metadata journal; and

adding the additional metadata entries to the recovery list.

5. A system for recovering a source storage system, the system comprising a computer processor configured to execute instructions comprising:

intercepting write transactions issued by a host computer to the source storage system before the write transactions are received at the source storage system;

streaming the intercepted write transactions to a backup storage system;

upon receipt of the stream of intercepted write transactions at the backup storage system, recording metadata associated with the write transactions in a metadata journal at the backup storage system, and data associated with the write transactions in a data journal at the backup storage system;

after the recording metadata and data, allowing the write transactions issued by the host computer to be received at the source storage system;

periodically synthesizing backup snapshots of the source storage system using the metadata journal and data journal at the backup storage system;

receiving a request to recover data for the source storage system, the request comprising a point-in-time that is before a logical corruption of the source storage system;

synthesizing a recovery snapshot for the point-in-time using the metadata journal and data journal at the backup storage system;

identifying a difference between the recovery snapshot and a latest synthesized backup snapshot, the latest synthesized backup snapshot having been created for a point-in-time that is after the point-in-time of the recovery snapshot;

adding the difference to a recovery list as entries in the recovery list;

identifying metadata entries in the metadata journal at the backup storage system, wherein the metadata entries are not in the latest synthesized backup snapshot;

adding the metadata entries to the recovery list; and

transmitting data associated with entries in the recovery list to the source storage system.

6. The system of claim 5, further comprising:

identifying additional metadata entries in a data protection appliance memory at the backup storage system, wherein the additional metadata entries have not been written to the metadata journal; and

adding the additional metadata entries to the recovery list.