Detecting out-of-band (OOB) changes when replicating a source file system using an in-line system

• US 9,311,331 B2
• Filed: 08/27/2013
• Issued: 04/12/2016
• Est. Priority Date: 08/27/2013
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Beard, Derek, Hsiao, Duen-Wen, Yammine, Ghassan
• Primary Examiner(s): Ly, Anh
• Application Number:
  US14/011,718
• Publication Number:
  US 20150066852A1
• Time in Patent Office: 959 Days
• Field of Search: 707/625, 707/657, 707/637, 707/639, 707/640, 707/649, 707/692, 707/827, 707/613, 707/661, 707/610, 707/822, 707/E17.01, 707/E17.002, 707/E17.032, 707/E17.005, 711/100, 711/103, 711/122, 711/123, 711/135, 711/141, 711/154, 711/156, 711/162, 711/171, 711/E12.002, 709/203, 709/205, 709/213, 709/216, 709/217, 709/218, 709/219, 709/220, 709/226, 709/229, 709/230, 709/232, 709/239
• US Class Current: 1/1
• CPC Class Codes: G06F 16/11 File system administration, e.g. details of archiving or snapshots file system backup G06F11/14
• CPC Class Codes: G06F 16/119 Details of migration of file systems migration mechanisms in storage systems G06F3/0647
• CPC Class Codes: G06F 16/178 Techniques for file synchronisation in file systems
• CPC Class Codes: G06F 16/184 implemented as replicated file system

Abstract

Examples described herein include a computer system, positioned in-line with respect to a plurality of clients that actively use a source file system, to replicate a source file system on a target memory in presence of out-of-band events which alter the source file system.

Claims

1. A method for replicating changes, the method being implemented by one or more processors that are external to a source file system, the method comprising:

replicating at least a portion of the source file system on a target memory while a plurality of clients utilize the source file system;

generating an object identifier for each file system object that is replicated in the target memory, the object identifiers being based at least in part on metadata provided with each file system object in the source file system;

storing the object identifier, for each file system object that is replicated, in association with a corresponding file handle; and

handling requests from individual clients in the plurality of clients for file system objects of the source file system;

wherein handling requests includes;

receiving a given request that specifies a file handle;

retrieving, from the source file system, a set of metadata associated with the specified file handle;

determining, from the set of metadata, that the file handle identifies a first file system object on the source file system and a second file system object on the target memory by (i) generating an object identifier from the retrieved set of metadata, and (ii) determining that the generated object identifier does not match one of the stored object identifiers; and

updating the target memory so that the specified file handle identifies the first file system object.

2. The method of claim 1, wherein determining includes comparing a time stamp in the set of metadata with a corresponding time stamp associated with the file handle in the target memory.

3. The method of claim 1, wherein the target memory corresponds to a cache.

4. The method of claim 1, wherein the target memory corresponds to a destination file system, and wherein replicating at least the portion of the source file system includes replicating the source file system on the destination file system while the source file system is in use by the plurality of clients.

5. A system positioned in-line between a plurality of clients and a source file system, the system comprising:

a memory resource to store instructions;

one or more processors using the instructions stored in the memory resource to;

replicate at least a portion of the source file system on a target memory while the plurality of clients utilize the source file system;

generate an object identifier for each file system object that is replicated in the target memory, the object identifiers being based at least in part on metadata provided with each file system object in the source file system;

store the object identifier, for each file system object that is replicated, in association with a corresponding file handle; and

handle requests from individual clients in the plurality of clients for file system objects of the source file system;

wherein handling requests includes;

receiving a given request that specifies a file handle;

retrieving, from the source file system, a set of metadata associated with the specified file handle;

determining, from the set of metadata, that the file handle identifies a first file system object on the source file system and a second file system object on the target memory by (i) generating an object identifier from the retrieved set of metadata, and (ii) determining that the generated object identifier does not match one of the stored object identifiers; and

updating the target memory so that the specified file handle identifies the first file system object.

6. The system of claim 5, wherein determining includes comparing a time stamp in the set of metadata with a corresponding time stamp associated with the file handle in the target memory.

7. The system of claim 5, wherein the target memory corresponds to a cache.

8. The system of claim 5, wherein the target memory corresponds to a destination file system, and wherein replicating at least the portion of the source file system includes replicating the source file system on the destination file system while the source file system is in use by the plurality of clients.

9. A non-transitory computer-readable medium that stores instructions, executable by one or more processors, to cause the one or more processors to perform operations that comprise:

replicating at least a portion of a source file system on a target memory while a plurality of clients utilize the source file system;

generating an object identifier for each file system object that is replicated in the target memory, the object identifiers being based at least in part on metadata provided with each file system object in the source file system;

storing the object identifier, for each file system object that is replicated, in association with a corresponding file handle; and

handling requests from individual clients in the plurality of clients for file system objects of the source file system;

wherein handling requests includes;

receiving a given request that specifies a file handle;

retrieving, from the source file system, a set of metadata associated with the specified file handle;

determining, from the set of metadata, that the file handle identifies a first file system object on the source file system and a second file system object on the target memory by (i) generating an object identifier from the retrieved set of metadata, and (ii) determining that the generated object identifier does not match one of the stored object identifiers; and

updating the target memory so that the specified file handle identifies the first file system object.

10. The non-transitory computer-readable medium of claim 9, wherein determining includes comparing a time stamp in the set of metadata with a corresponding time stamp associated with the file handle in the target memory.

11. The non-transitory computer-readable medium of claim 9, wherein the target memory corresponds to a cache.

12. The non-transitory computer-readable medium of claim 9, wherein the target memory corresponds to a destination file system, and wherein replicating at least the portion of the source file system includes replicating the source file system on the destination file system while the source file system is in use by the plurality of clients.