File server for long term data archive

• US 20060010177A1
• Filed: 07/09/2004
• Published: 01/12/2006
• Est. Priority Date: 07/09/2004
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kodama, Shoji
• Granted Patent: US 7,353,242 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/125 characterised by the use of retention policies retention policies for HSM systems G06F16/185
• CPC Class Codes: G06F 16/1827 Management specifically adapted to NAS management of storage area networks [SAN] G06F3/067
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

A NAS system including a NAS controller which processes file level input/output requests and controls the NAS system, and a storage apparatus having a controller which controls a storage device upon which plural volumes for storing data are represented. In the invention when at least a portion of data of a file stored on a volume is updated, the updated data is stored to an unused area of the volume, information is stored on the volume indicating that the updated data corresponding to original data stored in an original area is stored in the unused area so that subsequent accesses to the original of the updated data is directed to the updated data stored in the unused area, and the original of the updated data is retained in the original area, thereby implementing long term data archiving of the original of the updated data.

Claims

1. A Network Attached Storage (NAS) system for implementing long term data archiving comprising:

a NAS controller which processes file level input/output (I/O) requests and controls said NAS system; and

a storage apparatus having a controller and a storage device, controlled by said controller, upon which a plurality of volumes for storing data is represented,

wherein when at least a portion of data of a file stored on a volume included in said volumes is updated, the updated data is stored to an unused area of said volume and information is stored on said volume indicating that the updated data corresponding to original data stored in an original area is stored in said unused area so that subsequent accesses to the original of the updated data is directed to the updated data stored in said unused area, and

wherein the original of the updated data is retained in said original area, thereby implementing long term data archiving of the original of the updated data.

2. A NAS system according to claim 1, wherein said volumes include a cache volume and at least one data volume.

3. A NAS system according to claim 1, wherein said NAS system receives said file level I/O requests from servers through a network connected between said servers and said NAS system.

4. A NAS system according to claim 3, wherein each server executes application programs and includes a Network File System (NFS) sitting under a Virtual File System (VFS) layer of an operating system of the server so as to provide the application programs file level access to said NAS system via said network.

5. A NAS system according to claim 3, wherein each server executes application programs and includes a Common Interface File System (CIFS) sitting under a Virtual File System (VFS) layer of an operating system of the server so as to provide the application programs file level access to said NAS system via said network.

6. A NAS system according to one of claims 4 or 5, wherein said NAS controller comprises:

a NFS/CIFS server for processing NFS or CIFS file I/O requests; and

a Sequential Write File System (SWFS), sitting under a VFS layer of an operating system of said NAS controller, for managing files requested by file I/O requests that have been processed by said NFS/CIFS server.

7. A NAS system according to claim 6, wherein said SWFS manages files by:

(a) never overwriting a file stored in a data volume once the file is written to the data volume;

(b) If a file stored in a data volume needs to be modified, keeping the original file in the data volume and writing a modified file to another un-used location in the data volume;

(c) writing data from the first offset of a volume to the last offset sequentially,

(d) upon a data volume becoming filled with data, protecting the volume and using another data volume to write another data or update data; and

(c) If a retention period set to a data volume has expired, allowing the user to decide whether to keep or delete files stored in the data volume.

8. A NAS system according to claim 7, wherein according to (d) the volume is protected using a Write Once Read Many (WORM) Application Program Interface (API).

9. A NAS system according to claim 1, wherein said information stored on said volume relating said unused area in which the updated data is stored to an original area of the original of the updated data is an inode having a data structure which contains information about said file.

10. A NAS system according to claim 9, wherein a different inode is created for each file when a file system is created.

11. A NAS system according to claim 10, wherein each inode includes basic information about a file and data allocation information of the file,

wherein said basic information includes at least information identifying the inode, the size of the file and the time at which the file was last modified,

wherein said volume is divided into a plurality of disk blocks, and

wherein said data allocation information includes at least information identifying the disk blocks in the volume to which the file is stored.

12. A NAS system according to claim 11, wherein when said at least a portion of data of said file is updated and prior to said file being closed, said inode of said file is modified to identify disk blocks of the unused area to which the updated data is stored.

13. A NAS system according to claim 11, wherein the modified inode and an original of the modified inode are stored in the volume in a manner such that the modified inode is used as the inode of the file and the original of the modified inode is archived.

14. A NAS system according to claim 6, wherein said SWFS upon receipt of a file I/O request processed by said NFS/CIFS server determines whether said file I/O request is one of a FILE_OPEN request wherein a specified file is opened, a FILE_CLOSE request wherein a specified file is closed, a FILE_READ request wherein data is read from a specified file, a FILE_WRITE request wherein data written to a specified file, a FILE_DELETE request wherein a specified file is deleted, a FILE_CREATE request wherein a file is created, a CHANGE_ATTRIBUTE request wherein basic information in an inode of a specified file is changed, a SET_RETENTION request wherein a retention period is set to a specified file system, and a SHOW_OLD_VERSION request wherein older versions of a specified file are provided.

15. A NAS system according to claim 14, wherein when said file I/O request is a FILE_OPEN request said SWFS reads an inode of a specified file from a current data volume into a memory of said NAS controller and returns a file descriptor (FID) as a reference for the file to be opened file to said NFS/CIFS server which uses the FID to specify the opened file.

16. A NAS system according to claim 14, wherein when said file I/O request is a FILE_READ request, said SWFS checks if a requested area in said file is stored in a cache volume or a data volume by looking at data allocation information of the inode for said file, and if the requested area is stored in the cache volume, the SWFS reads data from the cache volume to the memory of the NAS controller, said NFS/CIFS server specifies a location in the memory to store read data, and said SWFS reads data from the data volume to memory of said NAS controller.

17. A NAS system according to claim 14, wherein when said file I/O request is a FILE_WRITE request, said SWFS allocates a sufficient number of un-used disk blocks in a cache volume in order to store received data, manages allocations of disk blocks for both cache volume and data volumes by using bitmap tables, modifies data allocation information of the inode of said file so that the inode points to the unused disk blocks, and writes the received data to the unused disk blocks.

18. A NAS system according to claim 14, wherein when said file I/O request is a FILE_CLOSE request, said SWFS allocates a sufficient number of un-used disk blocks in a data volume in order to store updated data in a cache volume, if a sufficient number of disk blocks are un-used, said SWFS copies data stored in a cache volume and pointed to by the inode of said file to the allocated disk blocks in the data volume, modifies data allocation information of the inode so that the inode points to the un-used disk blocks, allocates a sufficient number of un-used disk blocks in the data volume in order to store the modified inode, and if a sufficient number of disk blocks are un-used, said SWFS writes the modified inode to the allocated disk blocks in the data volume.

19. A NAS system according to claim 18, wherein if there is not a sufficient number of un-used disk blocks, the data volume is protected, a retention period is set and a new data volume is allocated upon which the write operation is performed.

20. A NAS system according to claim 14, wherein when said file I/O request is a CHANGE_ATTRIBUTE request, said SWFS sets received information to basic information entries of the inode of said file.

21. A NAS system according to claim 14, wherein when said file I/O request is a FILE_DELETE request, said SWFS opens a directory in which said file is contained, deletes an entry for said file from the opened directory file, closes the directory of said file, de-allocates the inode of said file.

22. A NAS system according to claim 14, wherein when said file I/O request is a FILE_CREATE request, said SWFS allocates a new inode which is not used for any file, opens a directory in which said file will be located, adds a new entry for said file and the allocated inode in the opened directory, and closes the directory.

23. A NAS system according to claim 14, wherein when said file I/O request is a SET_RETENTION_REQUEST request, said SWFS sets retention period information for all of data volumes that have been allocated to the file system.

24. A NAS system according to claim 14, wherein when said file I/O request is a SHOW_OLD_VERSION request, said SWFS finds old inodes of said file from data volumes, finds an inode having a modified time that is the closest to a time specified by a NFS/CIFS server and having a last modified time that does not exceed a specified time, copies the file pointed to by the inode from a data volume to a cache volume, and returns a file name and its location in the cache volume to said NFS/CIFS server.