Switch device, system, backup method and computer program

• US 20060080370A1
• Filed: 09/28/2005
• Published: 04/13/2006
• Est. Priority Date: 09/29/2004
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Yamakawa, Satoshi, Kajiki, Yoshihiro, Torii, Takashi
• Granted Patent: US 8,346,826 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1456 Hardware arrangements for backup
• CPC Class Codes: G06F 11/1466 to make the backup process non-disruptive
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• 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 16/1827 Management specifically adapted to NAS management of storage area networks [SAN] G06F3/067
• CPC Class Codes: G06F 16/192 Implementing virtual folder structures

Abstract

Disclosed is a system which includes at least one client, a plural number of file servers, each having a file system, and a switch logically arranged between the client and the plural file servers to provide file access services which virtually render the plural file services accessible as a single file system, termed a ‘pseudo file system’, when viewed from the terminal. The switch distributes a command for start of generation of snapshots to the plural file servers, which file servers formulate respective snapshots responsive to the command for start of formation of the snapshots. The switch sets the plural snapshots, generated by the plural file servers, so as to be associated with the file system structure of the virtual file system at the time of formation of the snapshots.

Claims

1. A backup management system comprising:

a plurality of file devices, each including a file system;

means for commanding said plurality of file devices to start the generation of snapshots, which are fixed images of said file systems at a certain point in time;

said plurality of file devices generating respective snapshots responsive to a command for starting the generation of said snapshots; and

means for setting a link across a plurality of snapshots to generate a virtual snapshot so that said plurality of snapshots generated by said file devices corresponds to a consolidated file system structure of said plurality of file systems at the time of snapshot generation;

whereby backup and/or restore may be made using said virtual snapshot.

2. A file access service system comprising:

at least one terminal;

a plurality of file devices, each including a file system; and

an intermediate device logically arranged between said terminal and said plurality of file devices, said intermediate device furnishing said terminal which a file access service which allows said terminal to access said plurality of file systems as a single file system, termed hereinafter a ‘

pseudo file system’

;

said intermediate device including means for commanding each of said plurality of file devices to start the generation of a snapshot which is a fixed image at a certain point in time of said file system of each of said plurality of file devices;

each of said plurality of file devices generating a snapshot responsive to said command from said intermediate device for starting to generate the snapshot;

said intermediate device also including means for setting a link across a plurality of said snapshots so that a plurality of said snapshots generated respectively by said plurality of file devices correspond to said pseudo file system at the time of generation of said snapshots.

3. The file access service system according to claim 2, wherein

said intermediate device holds, as the snapshot information relating to said pseudo file system, link information of junctions which connects said snapshots.

4. The file access service system according to claim 2, wherein

said terminal reads the snapshots generated by said file devices from said file devices and takes backup of a backup image corresponding to said snapshots in a recording device for backup.

5. The file access service system according to claim 2, further comprising

a backup control device;

said backup control device receiving, in taking backup, file systems of said plural of file devices, via said intermediate device, to take a backup in a recording backup device as a single file system structure virtualizing said plural file systems.

6. The file access service system according to claim 2, a backup control device communicating with a plurality of said file devices,

said backup control device in taking a backup, receiving plural file systems of said plural file devices via said intermediate device and taking a backup of said plural file systems in said recording backup device as a single virtual file system structure of said plural file systems.

7. The file access service system according to claim 6, wherein

said backup control device in restoration, sends backup data of said recording backup device to said intermediate device;

said intermediate device distributing the backup data, received from said backup control device, to a plurality of said file devices for restoral, in keeping with the pseudo file system information configured for allowing a plurality of said file systems to look as a single file system.

8. The file access service system according to claim 2, further comprising

a backup control device for communication with a plurality of said file devices;

said backup control device having an interface for communicating with said intermediate device;

said backup control device in taking a backup receiving plural snapshots of said plural file devices via said intermediate device;

a link being set across said plural snapshots;

said plural snapshots, said link is set to, being backed up in said recording backup device.

9. The file access service system according to claim 8, wherein

said backup control device, in restoration, sends the backup data of said recording backup device to said intermediate device;

said intermediate device distributing and transmitting said plural snapshots to said plural file devices;

said plural file devices restoring the file systems using said snapshots transmitted thereto.

10. The file access service system according to claim 2, wherein said intermediate device is a switch device logically arranged between said terminal forming a client and a plurality of server devices each forming said file device;

said switch device receiving a file access request from said client;

said switch device distributing said file access request to appropriate server devices and transmitting the so distributed file access request;

said switch device receiving a response to said file access request transmitted from said server devices to transfer said response to said terminal which transmitted said file access request.

11. The file access service system according to claim 10, wherein said switch device stores and supervises, as said pseudo file system information, the junction information connecting directory trees constituting a unified single directory tree combined from the directory trees of said plural file systems, as said pseudo file system information.

12. A method for taking a backup in a file access service system comprising

at least one terminal;

a plurality of file devices, each including a file system; and

an intermediate device logically arranged between said terminal and said file devices;

said intermediate device providing file access services which virtually render said plural file services accessible as a single file system, termed a ‘

pseudo file system’

, when viewed from said terminal;

said method comprising the steps of

said intermediate device distributing a command for starting to generate a snapshot which is a fixed image of a file system at a certain point in time, to a plurality of said file devices;

said plural file devices receiving a command for starting to take snapshots from said intermediate device to formulate respective snapshots; and

said intermediate device setting a link across a plurality of said snapshots so that said snapshots generated by said file devices are in correspondence with said pseudo-file system at the time of generation of said snapshots.

13. The backup taking method according to claim 12, further comprising the step of

said intermediate device holding the link information of junctions connecting said snapshots as the snapshot information corresponding to said pseudo-file system.

14. A switch device logically arranged between at least one client and a plurality of file servers, each provided with a file system, for providing file access services which virtually render said plural file systems accessible as a single file system, termed a ‘

pseudo file system’

, when viewed from said client;

said switch device comprising;

a unit that distributes a command for starting to generate a snapshot, which is a fixed image of a file system at a certain point in time, to a plurality of said file servers; and

a unit that sets a link across a plurality of said snapshots so that said snapshots generated by said file servers on receipt of a command for starting to generate the snapshots so that said snapshots corresponds with said pseudo-file system at the time of generation of said snapshots.

15. The switch device according to claim 14, wherein

the link information of junctions connecting said snapshots is retained as the snapshot information corresponding to said pseudo-file system.

16. The switch device according to claim 14, further comprising a unit that exercises control for halting the access to said file systems in starting to take snapshots.

17. The switch device according to claim 16, further comprising

a unit that exercises control for first confirming synchronization relating to file access across said file servers and said client and for subsequently allowing said plural file devices to take snapshots.

18. The backup taking method according to claim 14, further comprising a unit that exercises control for first generating snapshots and for subsequently restarting to access said file systems.

19. A program for a computer forming a switch device logically arranged between at least one client and a plurality of file servers, each provided with a file system, for supplying said client with a file access service which allows said client to access said plural file systems as a single file system, termed a ‘

pseudo file system’

, said program causing said computer to execute the processing of

distributing a command for starting to generate a snapshot which is a fixed image of a file system at a certain point in time, to a plurality of said file servers; and

setting a link across a plurality of said snapshots so that said snapshots generated by said file servers on receipt of a command for staring to generate the snapshots, so that said snapshots are in correspondence with said pseudo-file system at the time of generation of said snapshots.

20. The program according to claim 19, wherein the link information of junctions connecting said snapshots is retained as the snapshot information corresponding to said pseudo-file system.