File system

Abstract

The present invention provides a file system capable of reducing time taken to switch I/O paths, and hiding the process of switching the I/O paths from the user. In a system of the present invention in which a file ID is defined for each file, upon receiving a request for accessing a file specifying a file ID from a user, a file server refers to a file management table to obtain a logical disk ID for accessing the file. The file server then refers to a logical disk management table to obtain an I/O path corresponding to the logical disk ID, and accesses a physical disk device by use of the obtained I/O path. When a fault has occurred in an operational I/O path, a file server rewrites the logical disk management tables in all nodes to change the I/O path.

1 . A file system including at least one node having a file server which processes files distributed and managed in a plurality of physical disk devices, wherein a file ID is defined for each of said files, said node comprising: 
 a file management table including records each composed of a file ID and a logical disk ID of a logical disk, said logical disk storing a file corresponding to said file ID;    a logical disk management table including records each composed of said logical disk ID and one or more I/O paths, said one or more I/O paths being used for accessing one or more physical disk devices corresponding to said logical disk;    wherein upon receiving a request for accessing a file specifying a file ID from a user, the file server refers to said file management table; determines a logical disk ID of a logical disk storing said file based on said file ID; refers to said logical disk management table to determine an I/O path for accessing a physical disk device corresponding to said logical disk based on said logical disk ID; and accesses the physical disk device by use of the determined I/O path.