File system image transfer

• US 6,604,118 B2
• Filed: 07/31/1998
• Issued: 08/05/2003
• Est. Priority Date: 07/31/1998
• Status: Expired due to Term

• Current Assignee: NetApp, Inc.
• Original Assignee: Network Appliance Incorporated (NetApp, Inc.)
• Inventors: Hitz, David, Kleiman, Steven, Harris, Guy, OʼMalley, Sean
• Primary Examiner(s): Metjahic, Safet
• Assistant Examiner(s): LE, UYEN T
• Application Number:
  US09/127,497
• Publication Number:
  US 20010044807A1
• Time in Patent Office: 1,831 Days
• Field of Search: 707/203, 707/204, 707/205, 707/100, 707/103, 707/104, 707/200, 707/201, 707/10, 707/101, 707/102, 707/104.1, 707/202
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 11/1448 Management of the data involved in backup or backup restore
• CPC Class Codes: G06F 11/1456 Hardware arrangements for backup
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99954 Version management

Abstract

The invention provides a method and system for duplicating all or part of a file system while maintaining consistent copies of the file system. The file server maintains a set of snapshots, each indicating a set of storage blocks making up a consistent copy of the file system as it was at a known time. Each snapshot can be used for a purpose other than maintaining the coherency of the file system, such as duplicating or transferring a backup copy of the file system to a destination storage medium. In a preferred embodiment, the snapshots can be manipulated to identify sets of storage blocks in the file system for incremental backup or copying, or to provide a file system backup that is both complete and relatively inexpensive.

Claims

1. A method for identifying storage blocks in a file system having a plurality of storage blocks, comprising the steps of:

identifying a first storage image indicating a first set of member storage blocks selected from the plurality, the first storage image including a first bit plane indicating which member storage blocks are in the first storage image;

identifying a second storage image indicating a second set of member storage blocks selected from the plurality, the second storage image including a second bit plane indicating which member storage blocks are in the second storage image;

performing a logical operation on the first bit plane and the second bit plane to determine a logical difference between the first storage image and the second storage image;

wherein at least the first storage image or the second storage image indicates member storage blocks forming a consistent file system other than an active file system.

7. A method as in claim 1, wherein the first bit plane and the second bit plane each form a column of a collection of bit planes, each row in the collection representing a storage block.

2. A method for identifying storage blocks in a file system having a plurality of storage blocks, comprising the steps of:

identifying a first storage image indicating a first set of member storage blocks selected from the plurality, the first storage image including a first bit plane indicating which member storage blocks are in the first storage image;

identifying a second storage image indicating a second set of member storage blocks selected from the plurality, the second storage image including a second bit plane indicating which member storage blocks are in the second storage image;

performing a logical operation on the first bit plane and the second bit plane to determine a logical sum of the first storage image and the second storage image;

wherein at least the first storage image or the second storage image indicates member storage blocks forming a consistent file system other than an active file system.

8. A method as in claim 2, wherein the first bit plane and the second bit plane each form a column of a collection of bit planes, each row in the collection representing a storage block.

3. A memory storing information including instructions, the instructions executable by a processor to identify storage blocks in a file system having a plurality of storage blocks, the instructions comprising:

identifying a first storage image indicating a first set of member storage blocks selected from the plurality, the first storage image including a first bit plane indicating which member storage blocks are in the first storage image;

identifying a second storage image indicating a second set of member storage blocks selected from the plurality, the second storage image including a second bit plane indicating which member storage blocks are in the second storage image;

performing a logical operation on the first bit plane and the second bit plane to determine a logical difference between the first storage image and the second storage image;

wherein at least the first storage image or the second storage image indicates member storage blocks forming a consistent file system other than an active file system.

9. A memory as in claim 3, wherein the first bit plane and the second bit plane each form a column of a collection of bit planes, each row in the collection representing a storage block.

4. A memory storing information including instructions, the instructions executable by a processor to identify storage blocks in a file system having a plurality of storage blocks, the instructions comprising:

identifying a first storage image indicating a first set of member storage blocks selected from the plurality, the first storage image including a first bit plane indicating which member storage blocks are in the first storage image;

identifying a second storage image indicating a second set of member storage blocks selected from the plurality, the second storage image including a second bit plane indicating which member storage blocks are in the second storage image;

performing a logical operation on the first bit plane and the second bit plane to determine a logical sum of the first storage image and the second storage image;

wherein at least the first storage image or the second storage image indicates member storage blocks forming a consistent file system other than an active file system.

10. A memory as in claim 4, wherein the first bit plane and the second bit plane each form a column of a collection of bit planes, each row in the collection representing a storage block.

5. An apparatus including:

a storage medium that stores a file system having a plurality of storage blocks;

a processor that executes instructions; and

a memory that stores the instructions, the instructions executable by the processor to identify storage blocks in the file system, the instructions comprising;

(a) identifying a first storage image indicating a first set of member storage blocks selected from the plurality, the first storage image including a first bit plane indicating which member storage blocks are in the first storage image, (b) identifying a second storage image indicating a second set of member storage blocks selected from the plurality, the second storage image including a second bit plane indicating which member storage blocks are in the second storage image, (c) performing a logical operation on the first bit plane and the second bit plane to determine a logical difference between the first storage image and the second storage image, wherein at least the first storage image or the second storage image indicates member storage blocks forming a consistent file system other than an active file system.

11. An apparatus as in claim 5, wherein the first bit plane and the second bit plane each form a column of a collection of bit planes, each row in the collection representing a storage block.

6. An apparatus including:

a storage medium that stores a file system having a plurality of storage blocks;

a processor that executes instructions; and

a memory that stores the instructions, the instructions executable by the processor to identify storage blocks in the file system, the instructions comprising;

(a) identifying a first storage image indicating a first set of member storage blocks selected from the plurality, the first storage image including a first bit plane indicating which member storage blocks are in the first blocks selected from the plurality, the second storage image including a second bit plane indicating which member storage blocks are in the second storage image, (c) performing a logical operation on the first bit plane and the second bit plane to determine a logical sum of the first storage image and the second storage image, wherein at least the first storage image or the second storage image indicates member storage blocks forming a consistent file system other than an active file system.

12. An apparatus as in claim 6, wherein the first bit plane and the second bit plane each form a column of a collection of bit planes, each row in the collection representing a storage block.