File system capable of generating snapshots and providing fast sequential read access

• US 8,909,885 B2
• Filed: 08/12/2013
• Issued: 12/09/2014
• Est. Priority Date: 03/29/2007
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Corbett, Peter F., Kazar, Michael
• Primary Examiner(s): Choe, Yong
• Assistant Examiner(s): GIARDINO JR, MARK A
• Application Number:
  US13/964,550
• Publication Number:
  US 20130332688A1
• Time in Patent Office: 484 Days
• Field of Search: 711/112, 711/153, 711/162, 707/639
• US Class Current: 711/162
• CPC Class Codes: G06F 12/00 Accessing, addressing or allocating within memory systems or architectures digital input from, or digital output to record carriers, e.g. to disk storage units, G06F3/06
• CPC Class Codes: G06F 13/00 Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units interface circuits for specific input/output devices G06F3/00 ; multiprogram control therefor G06F9/46; multiprocessor systems G06F15/16
• CPC Class Codes: G06F 13/28 using burst mode transfer, e.g. direct memory access DMA, cycle steal G06F13/32 takes precedence
• 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 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0643 Management of files
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

An on-disk structure of a file system has the capability to generate snapshots and provide fast sequential read access to data containers, such as files. The on-disk structure arranges sequential portions of files on disk within regions, wherein each region comprises a predetermined amount of disk space represented by blocks and wherein the data of the files stored within each region may or may not be stored sequentially within the region. In addition, the on-disk structure accommodates a plurality of types of regions, including (i) active regions that contain active file system data for large files, (ii) snapshot regions that contain “copy out” snapshot data for the large files and (iii) metadata regions that contain metadata, as well as directories and small files.

Claims

1. A method for providing a structure of a file system stored on a plurality of storage devices executing on a storage system, the file system capable of generating snapshots and providing fast sequential read access to a data container stored on the storage devices, the method comprising:

arranging sequential portions of the data container into a plurality of regions on the storage devices, each region including a predetermined amount of storage space represented by blocks on the storage devices;

organizing the plurality of regions as a plurality of active regions, each active region allocated for a different sequential portion of the data container and configured to store active file system data and snapshot data for the different sequential portion of the data container, wherein first blocks in a portion of the active region are marked as one of active for use in an active file system, for use in one or more snapshots, and free; and

if an active block is marked as for use in the one or more snapshots, preserving the active block within the active region without overwriting the active block with new active data, and writing the new active data to free space within the active region.

2. The method of claim 1 wherein the plurality of regions further comprises one or more metadata regions configured to store metadata.

3. The method of claim 1 further comprising allocating at least one active region in response to an event associated with the data container, wherein the event includes a request to create or extend the data container in which to store the active data associated with the data container.

4. The method of claim 1 wherein if the active block is required by the one or more snapshots, writing the new active data to any block marked as free in the free space within the active region.

5. The method of claim 1 further comprising, in response to a request to create the data container, allocating at least one active region.

6. The method of claim 1 further comprising:

allocating an additional active region for an additional sequential portion of the data container;

storing additional active data for the data container in a first portion of the additional active region; and

storing additional snapshot data in a second portion of the additional active region.

7. A system, comprising:

a storage system having a processor and coupled to one or more storage devices including storage space, the storage system configured to provide storage services relating to organization of information on the storage devices;

a storage operating system executed by the processor and configured to generate a snapshot and providing sequential read access to a data container stored on the storage devices, the storage operating system further configured to apportion the storage space into regions, including a plurality of active regions, where each active region is allocated for a different sequential portion of the data container and configured to store active file system data and snapshot data for the different sequential portion of the data container; and

the storage operating system executed by the processor further configured to preserve an active block within the active region and write new active data to free space within the active region if the active block is marked for use in one or more snapshots.

8. The system of claim 7 wherein the storage operating system executed by the processor further is configured to overwrite the active block with the new data if the active block is required by the one or more snapshots.

9. The system of claim 8 wherein first blocks in a portion of the active region are marked as one of active for use in an active file system, active for use in one or more snapshots, and free.

10. The system of claim 8 wherein the storage devices are disks having disk space.

11. The system of claim 8 wherein the active region comprises a predetermined amount of storage space represented by blocks.

12. The system of claim 8 wherein the data container is one of a file and a logical unit.

13. Apparatus configured to provide a structure of a file system executed by a processor and including one or more storage devices, the file system configured to generate snapshots and provide fast sequential read access to a data container stored on the storage devices, comprising:

means for arranging sequential portions of the data container into a plurality of regions on the storage devices, each region including a predetermined amount of space represented by blocks on the storage devices;

means for organizing the plurality of regions as active regions and other regions, each active region allocated for a different sequential portion of the data container and containing active file system data and snapshot data for the different sequential portion of the data container, wherein first blocks in a portion of the active region are marked as one of active for use in an active file system, for use in one or more snapshots, and free; and

means for preserving an active block within the active region and writing new active data to free space within the active region if the active block is not required by the one or more snapshots.

14. The apparatus of claim 13 further comprising means for transitioning the active block to become a snapshot block of the data container and means for writing the new active data to any block marked as free in the free space within the active region.