File server system providing direct data sharing between clients with a server acting as an arbiter and coordinator

• US 7,120,631 B1
• Filed: 12/21/2001
• Issued: 10/10/2006
• Est. Priority Date: 12/21/2001
• Status: Expired due to Term

• Current Assignee: EMC Corporation (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Vahalia, Uresh K., Tzelnic, Percy
• Primary Examiner(s): Follansbee, John
• Assistant Examiner(s): Nguyen, Dustin
• Application Number:
  US10/032,161
• Time in Patent Office: 1,754 Days
• Field of Search: 707/8, 707/10, 707/103, 710/200, 709/217, 709/226, 709/229, 711/152, 718/104
• US Class Current: 1/1
• CPC Class Codes: G06F 16/1774 Locking methods, e.g. locking methods for file systems allowing shared and concurrent access to files
• CPC Class Codes: Y10S 707/99938 Concurrency, e.g. lock management in shared database

Abstract

A client is permitted to send data access commands directly to network data storage of a network file server after obtaining a lock on at least a portion of the file and obtaining metadata indicating storage locations for the data in the data storage. For example, the client sends to the file server at least one request for access to a file. In response, the file server grants a lock to the client, and returns to the client metadata of the file including information specifying data storage locations in the network data storage for storing data of the file. The client receives the metadata, and uses the metadata to produce at least one data access command for accessing the data storage locations in the network storage. The client sends the data access command to the network data storage to read or write data to the file. For a write operation, the client may modify the metadata. When the client is finished writing to the file, the client returns any modified metadata to the file server.

Claims

1. A method of accessing data stored in a data storage location in a data storage device, the method comprising:

(a) a server receiving from a client a request for accessing data related to a file, and wherein the server is in communication with a data storage device including data storage locations and the server managing locks on files having data stored in the data storage device;

(b) in response to the request for data, the server returning to the client metadata of the file including information specifying a data storage location for the file and granting to the client a lock on at least a portion of the file to be used when accessing data that is at least a portion of the file; and

(c) using the metadata of the file received from the server, the client producing at least one data access command based on the metadata received from the server for accessing the data storage location and sending the at least one data access command produced from the metadata received from the server to the data storage device for accessing data stored on the data storage device that comprises at least a portion of the file for which the lock is granted.

2. The method as claimed in claim 1, wherein a plurality of clients share read-write access to the file, and the server grants respective read locks and write locks to the clients.

3. The method as claimed in claim 1, wherein the client writes data to the data storage location, modifies the metadata from server in accordance with the data storage location to which the data is written, and sends the modified metadata to the server.

4. The method as claimed in claim 3, wherein the client sends the modified metadata to the server after the client writes the data to the data storage location.

5. The method as claimed in claim 1, wherein the client has a lock manager that responds to a request from an application process of the client for access to the file by granting to the application process a local file lock on at least a portion of the file, and then sending to the server the request for access to the file.

6. The method as claimed in claim 5, wherein the method includes dynamically linking application programs of the client with input-output related operating system routines of the client, the input-output related operating system routines intercepting file access calls from client application processes to send file access requests to the server to obtain from the server locks upon at least a portion of each of the files, to obtain metadata from the server for producing data access commands for accessing data storage locations, to produce the data access commands from the metadata, and to send the data access commands to the server in order to access the data storage locations.

7. The method as claimed in claim 6, wherein the data access command is a write command for a write operation upon at least a portion of the file, and wherein the method includes the client writing the data to the data storage locations, modifying the metadata from the server in accordance with the write operation upon at least a portion of the file, and sending the modified metadata to the server.

8. The method as claimed in claim 7, wherein the client sends the modified metadata to the server after the client writes the data to the data storage location.

9. The method as claimed in claim 8, wherein the client performs asynchronous write operations upon the data storage locations, and wherein the client sends the modified metadata to the server in response to a commit request from an application process of the client.

10. The method as claimed in claim 9, wherein the client performs asynchronous write operations upon the data storage locations, and wherein the client sends the modified metadata to the server when the client requests the server to close the file.

11. A program product containing a program for a server and a client, wherein the server and the client are in communication with at least one data storage device including data storage locations for storing a file, wherein the program is executable for responding to each request for data that comprises at least a portion of a file stored in the at least one data storage device by:

enabling the server to respond to a request for data from a client for access to at least a portion of the file, by returning to the client metadata of the file including information specifying a data storage location for the file, and wherein the server is in communication with a data storage device and the server is further enabled by the program for managing locks on files having data stored in the data storage device and for granting a lock on at least a portion of the file to be used by the client when accessing data that comprises at least a portion of the file; and

enabling the client to use the metadata of the file received from the server to produce at least one data access command based on the metadata received from the server for accessing the data storage location and sending the at least one data access command produced from the metadata received from the server to the data storage device for accessing data stored on the data storage device that comprises at least a portion of the file for which the lock is granted.

12. The program product as claimed in claim 11, wherein a plurality of clients share read-write access to the file, and the server grants respective read locks and write locks to the clients.

13. The program product as claimed in claim 11, wherein the client writes data to the data storage location, modifies the metadata from the server in accordance with the data storage location to which the data is written, and sends the modified metadata to the server.

14. The program product as claimed in claim 13, wherein the client sends the modified metadata to the server after the client writes the data to the data storage location.