Data integrity for data storage devices shared by multiple hosts via a network

Abstract

Access by multiple hosts, such as computers, to a data storage device by way of a network while maintaining data integrity. In one embodiment, a method for accessing the storage device includes acquiring a resource “lock” that provides exclusive access to one of the hosts at a time. In another embodiment, the file systems of a first and second host provide file system attributes stored in a storage device to provide mutually exclusive access for each host to free blocks of the device. In another embodiment, a networked system contains a first host having exclusive direct access to a storage device over a digital network. A second host requiring access to the storage device communicates with the first host by way of the digital network. File access requests generated by the second host are transferred by a redirection filter driver within the second host to the first host.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a divisional patent application of U.S. patent application Ser. No. 10 / 951,474, filed Sep. 27, 2004 and entitled “Data Integrity for Data Storage Devices Shared by Multiple Hosts Via a Network;” which claims the benefit under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 60 / 506,829, filed Sep. 26, 2003 and entitled “Device-Level Data Integrity Scheme for Data Devices Shared by Multiple Hosts through LAN;” and which claims the benefit under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 60 / 590,722, filed Jul. 22, 2004 and entitled “Low-Level Communication Layers and Device Employing Same;” and which claims the benefit under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 60 / 581,691, filed Jun. 21, 2004 and entitled “File System Features That Enable a Storage Device to Be Shared Directly by Multiple Hosts at Device Level;” the disclosures of which are hereby incorporated herein by reference in the...

AI Technical Summary

Problems solved by technology

However, in such a network a complete computer system or host providing a network file system is required for each data storage device added to the network, thus significantly increasing the cost of the system.

In addition, the usage of files remotely accessible through network file systems typically is limited compared to what is possible by way of direct access of the files from a data storage device, such as a hard disc drive.

However, given that such a system provides no centralized control of data transfers between the hosts and the storage device, data integrity is a potential problem.

For example, with each host of the system writing and reading various portions of the storage device, one host may easily overwrite portions of files previously written by another host, thus possibly causing partial or total loss of the data contained in the files.

Further, no guarantee exists that the file will not occupy several discontinuous series of sectors on the data storage device.

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