Method and system for remote data recovery

• US 7,783,606 B2
• Filed: 04/28/2006
• Issued: 08/24/2010
• Est. Priority Date: 02/04/2004
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Johnston, Craig, Chang, Yafen Peggy, Stager, Roger Keith
• Primary Examiner(s): Vital; Pierre M
• Assistant Examiner(s): OBISESAN, AUGUSTINE KUNLE
• Application Number:
  US11/413,327
• Publication Number:
  US 20060195493A1
• Time in Patent Office: 1,579 Days
• Field of Search: None
• US Class Current: 707/657
• CPC Class Codes: G06F 11/1466 to make the backup process non-disruptive
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 2201/82 Solving problems relating to consistency ensuring consistency in mirrored systems G06F11/2064
• 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 generating a snapshot in a consistent state is disclosed. The system comprises a host computer, a primary data storage, a data protection unit, and a secondary data storage. The data protection unit monitors a state of an email application which is running on the host computer. The data protection unit generates a snapshot of data stored in a primary data storage when the email application is in a consistent state, and stores the snapshot on a secondary storage. In the event of a system failure, the data is recovered using the last snapshot. A method and system for recovering email data from a snapshot in a consistent state using a client is also disclosed.

Claims

1. A method comprising:

monitoring memory activity of an application running on a host computer having a memory, wherein the monitoring is carried out by a data protection unit physically distinct from the host computer without suspending the application, wherein the application is configured to temporarily store output data in the memory before the data is output to a primary data volume including a first aggregation of one or more physical storage devices, and wherein monitoring memory activity of the application includes monitoring to detect when the temporarily stored output data is output to the primary data volume;

based on the memory activity, detecting when the memory contains no pending data associated with the application to be written to the primary data volume;

in response to detecting that the memory contains no pending data, generating a snapshot of data stored in the primary data volume;

storing the snapshot on a secondary data volume including a second aggregation of one or more physical storage devices;

receiving a request for email data from a remote client by an internet message access protocol (IMAP) server on the data protection unit;

providing a list of snapshots from the IMAP server to the remote client;

receiving from the remote client a selection of a snapshot from the list of snapshots;

parsing the selected snapshot for email data; and

providing the email data to the remote client.

2. The method of claim 1 wherein the memory activity is determined by using an indication generated by the application.

3. The method of claim 2 wherein the indication is a bit indicating flushing of a buffer to the primary data volume.

4. The method of claim 2 wherein the indication is a state of a journaling file system log, whereby the data protection unit determines that the memory contains no pending data at a point in time when the log is empty.

5. The method of claim 1 wherein the application is an email application.

6. The method of claim 1 wherein the remote client is an email client.

7. The method of claim 1 wherein the email data is at least one of an email folder, email mailbox, email directory, individual email message, and email database.

8. A system for backing up data, the system comprising:

a host computer having a memory and configured to run an email application;

a primary data volume in communication with the host computer and configured to store email data, wherein the email application is configured to temporarily store output data in the memory before the data is output to the primary data volume;

a data protection unit physically distinct from the host computer and in communication with the host computer and configured to monitor memory activity of the email application without suspending the email application, wherein monitoring memory activity of the application includes monitoring to detect when the temporarily stored output data is output to the primary data volume, and to generate a snapshot for the stored email data when the monitoring detects that the email application has no pending data to be written to the primary data volume;

a secondary data volume in communication with the data protection unit and configured to store the snapshot; and

an email client in communication with the data protection unit, wherein the data protection unit includes a server for interfacing between the data protection unit and the email client for recovering email data.

9. The system of claim 8 wherein the email application generates an indication of the memory activity, whereby the memory activity is determined using the indication.

10. The system of claim 9 wherein the indication is a bit indicating flushing of a buffer to the primary data volume.

11. The system of claim 9 wherein the indication is a state of a journaling file system log, whereby the data protection unit determines that the memory contains no pending data at a point in time when the log is empty.

12. The system of claim 8 wherein the data protection unit controls both the primary data volume and the secondary data volume.

13. The system of claim 8 further comprising a switch for coupling the primary data volume and the data protection unit to the host computer.

14. The system of claim 8 further comprising:

an email database interface in communication with the server;

a database parser in communication with the email database interface;

a plurality of snapshots stored in a database, the database in communication with the database parser, wherein the email client selects one of the plurality of snapshots at a predetermined timestamp from a list of snapshots requested by the email client; and

wherein the selected snapshot is parsed by the database parser for email data requested by the email client and the requested email data is provided to the email client by the server.

15. The system of claim 14 wherein the email data is parsed by the database parser based on the type of email data.

16. The system of claim 8 wherein the email data is at least one of an email folder, email mailbox, email directory, individual email message, and email database.

17. A method for backing up data and recovering email data, the method comprising:

running an application on a host computer having a memory, wherein the application is configured to temporarily store output data in the memory before the data is output to a primary data volume including a first aggregation of one or more physical storage devices;

generating a plurality of snapshots of data stored in the primary data volume, wherein the plurality of snapshots are generated by a data protection unit physically distinct from the host computer without suspending the application;

storing the plurality of snapshots on a secondary volume including a second aggregation of one or more physical storage devices;

identifying a snapshot among the plurality of snapshots, wherein identifying the snapshot includes determining when the temporarily stored output data was output to the primary data volume and wherein the identified snapshot is determined to have been generated when the memory had no pending data to be written to the primary data volume;

requesting email data from an internet message access protocol (IMAP) server on the data protection unit by a remote client;

parsing the identified snapshot for email data; and

providing the email data to the remote client.

18. The method of claim 17 wherein the identified snapshot is determined by inspecting a log of write streams.

19. The method of claim 17 wherein the application is an email application.

20. The method of claim 17 wherein the email data is at least one of an email folder, email mailbox, email directory, individual email message, and email database.

21. A computer-readable storage medium storing a set of instructions for execution by a general purpose computer, the set of instructions comprising:

a snapshot code segment for monitoring memory activity of an email application running on a host computer having a memory, wherein the application is configured to temporarily store output data in the memory before the data is output to a primary data volume including a first aggregation of one or more physical storage devices, and wherein monitoring memory activity of the application comprises monitoring to detect when the temporarily stored output data is output to the primary data volume, wherein the monitoring is carried out by a data protection unit physically distinct from the host computer without suspending the email application and generating a plurality of snapshots for stored email data in the primary data volume when the monitoring indicates that the email application has no pending data to be written to the primary data volume;

an email recovery code segment for providing an individual email message to an email client, wherein the email client selects one of the plurality of snapshots at a predetermined timestamp from a list of snapshots provided to the email client;

an email parsing code segment for parsing the selected snapshot for the individual email message requested by the email client, wherein the selected snapshot is parsed based on the type of email application; and

a communication code segment for communicating the individual email message to the email client.