File system over fully provisioned volume file in direct mode

• US 9,256,603 B1
• Filed: 06/28/2013
• Issued: 02/09/2016
• Est. Priority Date: 06/28/2013
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Bono, Jean-Pierre, Davenport, William C., de Forest, Miles A., Forrester, Walter C., Marko, Michal, Zhang, Ye, Armangau, Philippe
• Primary Examiner(s): Alam, Hosain
• Assistant Examiner(s): ALLEN, NICHOLAS E
• Application Number:
  US13/931,757
• Time in Patent Office: 956 Days
• Field of Search: 707/824
• US Class Current: 1/1
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: G06F 16/1824 implemented using Network-attached Storage [NAS] architecture distributed or networked storage systems G06F3/067; protocols for distributed storage of data in a network H04L67/1097

Abstract

A data storage system includes storage devices and a processing subsystem executing software forming a lower-deck file system and an upper-deck file system. The lower-deck file system presents a volume file from which storage is provided to the upper-deck file system, and units of storage of the storage devices are reserved to the upper-deck file system. The volume file is fully provisioned based on the reserved units of storage so that an out-of-space condition is not presented to the upper-deck file system. Reserved units of storage are dynamically added to the volume file to increase its allocated size in response to demand from the upper-deck file system, and a direct operating mode is used in which a block address in the lower-deck file system is obtained by a predetermined calculation from a corresponding block address in the volume file.

Claims

1. A data storage system for use by a file system consumer according to a file system interface, comprising:

one or more physical nonvolatile storage devices; and

a processing subsystem executing software to form a multi-level stack of functional components including a lower-deck file system and an upper-deck file system, the upper-deck file system providing the file system interface to the file system consumer, the lower-deck file system presenting a volume file from which storage is provided to the upper-deck file system, units of storage of the storage devices being reserved to the upper-deck file system, the volume file being fully provisioned based on the reserved units of storage so that an out-of-space condition is not presented to the upper-deck file system, the reserved units of storage being added dynamically to the volume file to increase its allocated size in response to demand from the upper-deck file system, the lower-deck file system operating in a direct mode in which a block address of a data block in the lower-deck file system is obtained by a predetermined calculation from a corresponding block address of a data block in the volume file,

wherein the units of storage are slices having a slice size at least ten times a block size of the data blocks,

and wherein slices are created from corresponding slice-size areas of the volume file with a generally arbitrary mapping between their respective locations, the slice-size areas at a given time including holes not currently provisioned and being replaced with data-storing slices as the upper-deck file system grows,

and wherein growth of the upper-deck file system is passed down to the lower-deck file system, and including allocating additional pool slices to the lower-deck file system to grow the size of the volume file accordingly.

2. A data storage system according to claim 1, wherein the slices are pool slices and the slice size is a pool slice size, and wherein the volume file is consumed by the upper-deck file system in upper slices having an upper slice size.

3. A data storage system according to claim 2, wherein the upper slice size is equal to the pool slice size and the upper slices are boundary aligned with the pool slices.

4. A data storage system according to claim 2, wherein the upper slice size is not equal to the pool slice size.

5. A method of operating a data storage system to provide file system functionality to a file system consumer according to a file system interface, the data storage system including one or more physical nonvolatile storage devices and a processing subsystem, comprising:

instantiating, in the processing subsystem, software to form a multi-level stack of functional components including a lower-deck file system and an upper-deck file system, the upper-deck file system providing the file system interface to the file system consumer; and

by the lower-deck file system, (i) presenting a volume file from which storage is provided to the upper-deck file system, units of storage of the storage devices being reserved to the upper-deck file system, the volume file being fully provisioned based on the reserved units of storage so that an out-of-space condition is not presented to the upper-deck file system, (ii) dynamically adding reserved units of storage to the volume file to increase its allocated size in response to demand from the upper-deck file system, and (iii) utilizing a direct operating mode in which a block address of a data block in the lower-deck file system is obtained by a predetermined calculation from a corresponding block address of a data block in the volume file,

wherein the units of storage are slices having a slice size at least ten times a block size of the data blocks,

and wherein slices are created from corresponding slice-size areas of the volume file with a generally arbitrary mapping between their respective locations, the slice-size areas at a given time including holes not currently provisioned and being replaced with data-storing slices as the upper-deck file system grows,

and wherein growth of the upper-deck file system is passed down to the lower-deck file system, and including allocating additional pool slices to the lower-deck file system to grow the size of the volume file accordingly.

6. A method according to claim 5, wherein the slices are pool slices and the slice size is a pool slice size, and wherein the volume file is consumed by the upper-deck file system in upper slices having an upper slice size.

7. A method according to claim 6, wherein the upper slice size is equal to the pool slice size and the upper slices are boundary aligned with the pool slices.

8. A method according to claim 6, wherein the upper slice size is not equal to the pool slice size.

9. A method according to claim 5, wherein the volume file is a primary file of the lower-deck file system, and the lower-deck file system includes one or more snapshot files storing respective point-in-time copies of the volume file, the point-in-time copies being snapshots of the upper-deck file system.

10. A method according to claim 5, wherein the lower-deck file systems is associated with a respective sparse volume providing an additional layer of mapping between the lower-deck file system and a pool of storage to enable the lower-deck file system to operate by accessing the sparse volume as an underlying volume.

11. A method according to claim 10, wherein the volume file presented by the upper-deck file system is also a sparse volume.