System and method for virtualizing network storages into a single file system view

• US 20030220985A1
• Filed: 01/03/2003
• Published: 11/27/2003
• Est. Priority Date: 05/24/2002
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Higuchi, Tatsuo, Okitsu, Jun, Kawamoto, Shinichi, Yasuda, Yoshiko, Ebata, Atsushi
• Granted Patent: US 7,606,871 B2
• Time in Patent Office: Days
• US Class Current: 709/219
• CPC Class Codes: G06F 3/0611 in relation to response time
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• 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]

Abstract

A virtualizing file system view method for virtualizing one or more network storage devices into a virtualized file system view network storage system wherein destination network storage information of stored files is compactly held regardless of the number of files, and files are separated into one or more file groups and the file groups managed in destination network storage units. Until now, managing network storage unit information in individual files was necessary however the virtualizing file system view method reduces the management information that must be held and efficiently utilizes network storage capacity without holding destination network storage information in individual files. The cost of rewriting information is also lowered during structural changes such as adding or deleting network storage units since storage destination network information can be rewritten in file groups.

Claims

1. A method for virtualizing a plurality of network storages connected to a network into a virtualized network storage which can be accessed from a client, the method comprising steps of:

creating a file group allocation table which recoding mutual correlation between each of a plurality of file groups, all of files to be accessed being grouped into said file groups according to a predetermined rule, and a destination network storage to store files belonging to the corresponding file group; and

when said client issues a file access request to said virtualized network storage, determining, according to said rule, a file group to which the objective file of said file access request belongs; and

,

finding a destination network storage of said file access request for accessing said objective file by referring said file group allocation table.

2. A method for virtualizing network storages into a virtualized network storage according to claim 1, wherein said rule derives the file group to which said objective file belongs from file identifying information of said objective file.

3. A method for virtualizing network storages into a virtualized network storage according to claim 1, wherein when said client issues a file read/write request or a write request to said virtualized storage system, a file group belonging to said file is found from information identifying said file and, a destination network storage of said file group is found by referring to said group allocation table, and reading and writing of said file is performed in said destination network storage device that was found.

4. A method for virtualizing network storage into a virtualized network storage according to claim 1, wherein when said client issues a directory generation request to said virtualizing file system view network storage system, said directory generation request is issued to all network storage devices within said virtualizing network storage system and a directory is generated in each network storage device.

5. A method for virtualizing network storage into a virtualized network storage according to claim 1, wherein

a group map is provided for giving the mutual relation between a file identifier and the file group that said file identified by said file identifier belongs to;

and

when said client issues a file generation request with the path name of said file for generation as the variable to said virtualizing file system view network storage system, a file identifier corresponding to the file of said path name is generated; and

said file group corresponding to said file identifier is found by utilizing said group map;

a destination network storage device of said file group is found by referring to said file group allocation table; and

said file is generated in said network storage device.

6. A method for virtualizing network storage into a virtualized network storage according to claim 5, wherein when said client issues a file read request or write request with the file identifier of the file to access and the corresponding handle as variables to said virtualized network storage, said file identifier is found from said handle, a file group corresponding to said file identifier is found by utilizing said group map, a destination network storage device of said file group is specified by referring to said file group allocation table, and file reading or writing is performed in said specified destination network storage device.

7. A method for virtualizing network storage into a virtualized network storage according to claim 5, wherein

a file system is provided within said virtualized network storage;

said file identifier is set as the inode number in said file system, and

said group map sets a hash function as a search key for said inode number, and

when said client issues a file generation request to said virtualizing network storage system specifying a path name,

a file for said path name is generated in said file system, and

said hash function is applied to the inode number of said generated file and said file group is found, said file group allocation table is referred to and a destination network storage device for said file group is found, and said file is generated in said designated network storage device.

8. A method for virtualizing network storage into a virtualized network storage according to claim 5, wherein when said client issues a file read request or write request to said virtualized network storage specifying the handle of the file to access, the inode number is found from said handle, said hash function is applied to said inode number and said file group found, said file group allocation table is referred to and said destination network storage device of said file group is specified, and reading or writing of said file in said specified network storage unit is performed.

9. A method for virtualizing network storage into a virtualized network storage according to claim 5, further including steps of:

when the file group for movement and the movement destination network storage device are applied,

finding the destination network storage device prior to moving said file group by using said file group allocation table,

moving all files belonging to said file group stored in said network storage device to said movement destination network storage device and,

revising a record of said network storage devices corresponding to said moved file group in said file group allocation table into said movement destination network storage device.

10. A method for virtualizing network storage into a virtualized network storage according to claim 9, wherein a file group corresponding to a file identifier is found utilizing said group map for each file identifier of files stored in said virtualized file system view network storage, and if said file group is said file group for movement, then said file identified by said file identifier is moved.

11. A method for virtualizing network storage into a virtualized network storage according to claim 9, wherein when adding a network storage device to said virtualizing file system view network storage system, said added network storage device is set in said movement destination network storage device and, one or more file groups are selected from among all file groups of said virtualizing file system view network storage system, and

one file group from among said selected file groups is set in said movement destination network storage device and said file is moved, and

said file movement is performed on all selected file groups.

12. A method for virtualizing network storage into a virtualized network storage according to claim 9, wherein when adding a network storage device to said virtualizing file system view network storage system, said added network storage device is set in said movement destination network storage device, and

one file group is selected from among file groups stored in a network storage device with the least available remaining capacity among network storage devices of said virtualizing file system view network storage system (step 1), and

file movement of said file group is performed with said file group as said file group for movement (step 2), and

said process is repeated until conditions for ending selection of said file groups and movement of files are satisfied.

13. A method for virtualizing network storage into a virtualized network storage according to claim 12, wherein said ending condition is a value below a threshold value predetermined as the differential between the maximum available capacity and minimum available capacity from among said remaining available capacity of each network storage device.

14. A method for virtualizing network storage into a virtualized network storage according to claim 9, wherein when deleting network storage devices from said virtualizing file system view network storage system,

one file group is selected from among all file groups stored in said network storage device for deletion where said file belongs and (step 1),

said file group is made a file group for movement (step 2), and

one network storage device other than said network storage device for deletion within said virtualizing file system view network storage system is selected and made said movement destination network storage device (step 3), and

file movement is performed (step 4), and

said step 1, step 2, step 3, step 4 are continued until files are no longer present in said network storage device for deletion.

15. A method for virtualizing network storage into a virtualized network storage according to claim 14, wherein said network storage device for selected as a network storage device for movement is a network storage device with the largest available remaining capacity.

16. A method for virtualizing network storage into a virtualized network storage according to claim 9, wherein when the available remaining capacity of a network storage device comprising said virtualizing file system view network storage system drops below a first threshold value, one file group is selected from among file groups said file belongs to stored in said network storage device and said file group is made said file group for movement (step 1), and

one network storage device other than said network storage device is selected and made a movement destination network storage device (step 2), and

the file is moved (step 3), and

said step 1, step 2, step 3, are continued until the remaining available capacity of the network storage device stored prior to moving of said file group for movement, exceeds a second threshold value.

17. A method for virtualizing network storage into a virtualized network storage according to claim 16, wherein said network storage device for movement in step 2, is the network storage device with the largest remaining available capacity.

18. A method for virtualizing network storage into a virtualized network storage according to claim 9, wherein when the differential between the maximum available remaining capacity and minimum available remaining capacity in each network storage unit comprising said virtualizing file system view network storage system exceeds a first threshold value, one file group is selected from among file groups said file belongs to stored in said network storage device and said file group is made said file group for movement (step 1), and

one network storage device other than said network storage device is selected and made a movement destination network storage device (step 2), and

said file is moved (step 3), and

said step 1, step 2, step 3, are continued until the differential in the remaining available capacity of said network storage device drops below a second threshold value.

19. A method for virtualizing network storage into a virtualized network storage according to claim 18, wherein said network storage device selected for movement in step 2, is the network storage device with the largest remaining available capacity.

24. A unifying method for existing network storage devices of a virtualizing file system view network storage system, wherein said unifying method connects a virtualizing network storage system made into a file system view by a virtualizing file system view method according to claim 1 and comprised of one or more network storage systems not storing even one file;

to a network connected to an existing network storage device storing a client file, and further incorporating said existing storage network still holding said file into said virtualizing network storage system; and

establishes a file group allocation for linking one storage device from among existing network storage devices and added network storage devices with said respective file group; and

generates new file identifiers for all files of said existing network storage device storing said file; and

refers to said file group allocation file for all of said file identifiers and finds said network storage device corresponding to said file identifier; and

when said network storage device is not said existing network storage device, said file is moved from said existing network storage device to said destination storage network of said file group.

25. A unifying method for existing network storage devices of a virtualizing file system view network storage system according to claim 24, wherein in said file group allocation, said destination network storage devices for all file groups are set to become existing network storage devices.

20. A virtualizing file system for a network storage devices for allowing said client to virtually access one or more network storage devices as one network storage system, wherein said virtualizing file system view device comprising,

a group map giving the mutual relation between a file identifier and the file group that said file identified by said file identifier belongs to;

a file group allocation table for recording the interrelation of said file group with said destination network storage device of said file group, and

a request processing means to process the request from said client, and

when said client issues a file access request to said virtualizing file system view network storage system, said request processing means finds the file identifier of said file for accessing, finds the file group corresponding to said file identifier by utilizing said group map, finds said destination network storage device of said file group by referring to said file group allocation table, and issues to said network storage device said file access request issued by said client.

21. A virtualizing file system according to claim 20, comprising a file movement means for moving a file stored in a network storage device within a network storage system virtualized by said virtualizing file system view device, to another network storage device;

and when movement of files is necessary, said file movement means moves the files in groups.

22. A virtualizing file system according to claim 20, further comprising a means to store files and, a network storage means for accessing said file storage means as a network storage device from said client connected to said network.

23. A virtualizing file system according to claim 22, wherein when a client issues a file access request to a virtualizing file system view network storage system comprised of one said virtualizing file system view device with network storage function and 0 or more network storage devices, and

when said request processing means for said virtualizing file system view device with network storage function is itself said network storage device storing said file of said file access request, then said network storage device issues said file access request issued from said client to its own network storage control means and accesses said file.