Patent ID: 7240122

Claim:
A migration destination file sharing device communicably connected to a migration source file sharing device and a host computer via a communications network, the migration destination file sharing device including: means for relating a plurality of migration source shared file systems of the migration source file sharing device to plurality of migration destination shared file systems of the migration destination file sharing device by shared file system basis and for determining a mount point for network-mounting one of the migration source shared file systems of the migration source file sharing device, which is migration-related to the shared file systems of the migration destination file sharing device, as a migration source shared file system onto the migration destination file sharing device, and the migration source shared file systems each having a plurality of files; means for migrating files from the migration source file sharing device to the migration destination file sharing device on a file by file basis per shared file system; means for setting or changing a migration status of each file; means for causing access from the host computer to be switched from the migration source file sharing device to the migration destination file sharing device; means for detecting a migration status, which at least includes a “being copied” status and a “copied” status, of a file of said one of the migration source shared file systems to which access has been requested by the host computer; first means for providing the file from said one file system of the migration destination file sharing device to the host computer during the per shared file system file migration in a case where the detected migration status of the file is the “copied” status where the file can be used from said one file system of the migration destination file sharing device; and second means for providing the file from said one file system of the migration source file sharing device to the host computer during the per shared file system file migration in a case where the detected migration status of the file is the “being copied” status where the file cannot be used from said one file system of the migration destination file sharing device.