Methods and systems for replicating an expandable storage volume

• US 9,069,710 B1
• Filed: 03/28/2012
• Issued: 06/30/2015
• Est. Priority Date: 03/28/2012
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Modukuri, Kiran K., Jennings, Logan R.
• Primary Examiner(s): Rutz, Jared
• Assistant Examiner(s): EDOUARD, JEAN C
• Application Number:
  US13/433,157
• Time in Patent Office: 1,189 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1456 Hardware arrangements for backup
• CPC Class Codes: G06F 11/2051 in regular structures
• CPC Class Codes: G06F 11/2071 using a plurality of controllers
• CPC Class Codes: G06F 11/2074 Asynchronous techniques
• CPC Class Codes: G06F 11/2082 Data synchronisation
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• 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 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

Machine implemented method for generating and accessing a point in time copy of an expandable storage volume in a network storage system is provided. The expandable storage volume includes a namespace for storing information for accessing data objects stored at a plurality of data constituent volumes managed by a plurality of nodes of the storage system. The method includes initiating a logical fence first for the namespace and then for the data constituent volumes for generating the point in time copy of the expandable storage volume. The logical fence filters out any information written after the fence is initiated from the point in time copy of the expandable storage volume.

Claims

1. A machine implemented method for generating a snapshot of an expandable storage volume in a network storage system, the expandable storage volume having a namespace for storing information for accessing data objects stored at one or more data constituent volumes, comprising:

initiating a logical fence first for the namespace and then for an object location subsystem (OLS) datastore to track data objects when moved within the one or more data constituent volumes and after that for the one or more data constituent volumes for generating the snapshot of the expandable storage volume, wherein the logical fence excludes any write request to write within the logical fence after the logical fence is created;

storing information regarding the snapshot of the expandable storage volume in a data structure such that the snapshot of the expandable storage volume is presented to the client as a single entity for accessing a snapshot of the namespace and snapshots of the one or more data constituent volumes;

after the snapshot of the expandable storage volume is generated, removing the logical fence in an order opposite to an order in which the fence was initiated;

receiving an object for accessing the snapshot of the expandable storage volume, the object including an identifier identifying the snapshot of the namespace and an identifier identifying the namespace;

retrieving an identifier identifying at least one of the snapshots of the one or more data constituent volume from the data structure; and

retrieving data associated with the snapshot of the data constituent volume based on the identifier of the snapshot of the data constituent volume.

2. The method of claim 1, wherein the data structure stores an identifier of the snapshot of the expandable storage volume, the identifier identifying the snapshot of the namespace, the identifier of the at least one snapshot of the one or more data constituent volumes, the identifier of the namespace and an identifier identifying each of the one or more data constituent volumes.

3. The method of claim 2, wherein the identifier of the namespace is used to obtain the identifier of one of the data constituent volumes and the identifier of the snapshot of the namespace is used to obtain the identifier of the snapshot of the one of the one or more data constituent volumes.

4. The method of claim 1, wherein the expandable storage volume includes a plurality of data constituent volumes managed by at least two different storage system nodes.

5. The method of claim 1, further comprising:

retrieving identifier information of the namespace and the one or more data constituent volumes using an identifier of the expandable storage volume from a volume data structure maintained by a storage system node.

6. The method of claim 1, wherein the namespace stores a directory namespace having a directory entry associated with a data object stored at the one or more data constituent volumes.

7. The method of claim 6, wherein the directory entry stores a pointer to a redirector file that includes an object locator of the data object.

8. A system comprising:

a memory containing machine readable medium comprising machine executable code having stored thereon instructions; and

a processor module coupled to the memory, the processor module configured to execute the machine executable code to;

initiate a logical fence first for a namespace and then for an object location subsystem (OLS) datastore to track data objects when moved within one or more data constituent volumes and after that for the one or more data constituent volumes for generating a snapshot of an expandable storage volume in a network storage system having the namespace for storing information for accessing data objects stored at the one or more data constituent volumes, wherein the logical fence excludes any write request to write within the logical fence after the logical fence is created;

store information regarding the snapshot of the expandable storage volume in a data structure such that the snapshot of the expandable storage volume is presented to the client as a single entity for accessing a snapshot of the namespace and snapshots of the one or more data constituent volumes;

remove the logical fence in an order opposite to an order in which the fence was initiated, after the snapshot of the expandable storage volume is generated;

receive an object for accessing the snapshot of the expandable storage volume, the object including an identifier identifying the snapshot of the namespace and an identifier identifying the namespace;

retrieve an identifier identifying at least one of the snapshots of the one or more data constituent volume from the data structure; and

retrieve data associated with the snapshot of the data constituent volume based on the identifier of the snapshot of the data constituent volume.

9. The system of claim 8 wherein the data structure stores an identifier of the snapshot of the expandable storage volume, the identifier identifying the snapshot of the namespace, the identifier of the at least one snapshot of the one or more data constituent volumes, the identifier of the namespace and an identifier identifying each of the one or more data constituent volumes.

10. The system of claim 9 wherein the identifier of the namespace is used to obtain the identifier of one of the data constituent volumes and the identifier of the snapshot of the namespace is used to obtain the identifier of the snapshot of the one of the one or more data constituent volumes.

11. The system of claim 8 wherein the expandable storage volume includes a plurality of data constituent volumes managed by at least two different storage system nodes.

12. The system of claim 8 further comprising code to:

retrieve identifier information of the namespace and the one or more data constituent volumes using an identifier of the expandable storage volume from a volume data structure maintained by a storage system node.

13. The system of claim 8 wherein the namespace stores a directory namespace having a directory entry associated with a data object stored at the one or more data constituent volumes.

14. A non-transitory, machine readable storage medium having stored thereon instructions for performing a method, comprising machine executable code which when executed by at least one machine, causes the machine to:

initiate a logical fence first for a namespace and then for an object location subsystem (OLS) datastore to track data objects when moved within one or more data constituent volumes and after that for the one or more data constituent volumes for generating a snapshot of an expandable storage volume in the network storage system having the namespace for storing information for accessing data objects stored at the one or more data constituent volumes, wherein the logical fence excludes any write request to write within the logical fence after the logical fence is created;

store information regarding the snapshot of the expandable storage volume in a data structure such that the snapshot of the expandable storage volume is presented to the client as a single entity for accessing a snapshot of the namespace and a-snapshots of the one or more data constituent volumes;

remove the logical fence in an order opposite to an order in which the fence was initiated, after the snapshot of the expandable storage volume is generated;

receive an object for accessing the snapshot of the expandable storage volume, the object including an identifier identifying the snapshot of the namespace and an identifier identifying the namespace;

retrieve an identifier identifying at least one of the snapshots of the one or more data constituent volume from the data structure; and

retrieve data associated with the snapshot of the data constituent volume based on the identifier of the snapshot of the data constituent volume.

15. The storage medium of claim 14 wherein the code causes the data structure stores an identifier of the snapshot of the expandable storage volume, the identifier identifying the snapshot of the namespace, the identifier of the at least one snapshot of the one or more data constituent volumes, the identifier of the namespace and an identifier identifying each of the one or more data constituent volumes.

16. The storage medium of claim 15 wherein the identifier of the namespace is used to obtain the identifier of one of the data constituent volumes and the identifier of the snapshot of the namespace is used to obtain the identifier of the snapshot of the one of the one or more data constituent volumes.

17. The storage medium of claim 14 wherein the expandable storage volume includes a plurality of data constituent volumes managed by at least two different storage system nodes.

18. The storage medium of claim 14 further comprising instructions to:

retrieve identifier information of the namespace and the one or more data constituent volumes using an identifier of the expandable storage volume from a volume data structure maintained by a storage system node.

19. The storage medium of claim 14 wherein the namespace stores a directory namespace having a directory entry associated with a data object stored at the one or more data constituent volumes.