초록 ▼

A remote file server managing a remote storage device and a local file server managing a local storage device are coupled to a communication network (e.g. the Internet). The local file server (A) replicates a file in the local storage device to the remote file server and, (B) if a first condition is

A remote file server managing a remote storage device and a local file server managing a local storage device are coupled to a communication network (e.g. the Internet). The local file server (A) replicates a file in the local storage device to the remote file server and, (B) if a first condition is satisfied, manages the replicated file which is the file from which the data is replicated as a migration target file. The local file server, even if the (B) is completed, does not delete the migration target file from the local storage device and, if the second condition is satisfied, deletes the migration target file from the local storage device.

대표청구항 ▼

1. A file server which is a local file server that is coupled to a communication network to which is coupled to a remote file server managing a remote storage device and that manages a local storage device, the file server comprising: a first communication interface device which is coupled to the co

1. A file server which is a local file server that is coupled to a communication network to which is coupled to a remote file server managing a remote storage device and that manages a local storage device, the file server comprising: a first communication interface device which is coupled to the communication network;a second communication interface device which is coupled to a user terminal for sending an access request that is either a read request or a write request specifying a file, and which is configured to receive the access request from the user terminal; anda processor which is coupled to the first and second interface devices,wherein the processor is configured to:(A) transfer a file in the local storage device to the remote file server;(B) manage the transferred file as a migration target file;(C) not delete the migration target file from the local storage device even when the (B) is completed, and delete the migration target file from the local storage device when a certain length of time has passed from the last access time when free capacity of the local storage device falls below a specified threshold;(K) acquire, from the remote file server, upon receiving a write request with respect to a stub of the migration target file that has been deleted from the local storage device, a file managed by the remote file server which is the link destination identified from this stub;(L) store the acquired file in the local storage device; and(M) update the acquired file in accordance with the write request received in the (K); andrelease the stub when performing the (K). 2. A file server according to claim 1, wherein the communication network is the Internet, and the second communication interface device is coupled to multiple user terminals. 3. A file server according to claim 2, wherein each user terminal sends an open request before the read request, and sends a close request after the read request, the processor is configured to:(E) update a count value of the migration target file in accordance with a first rule each time receiving the open request; and(F) update a count value of the migration target in accordance with a second rule each time receiving the close request. 4. A file server according to claim 1, wherein the processor is configured to: (H) manage the transferred file as a synchronization target file upon receiving a write request with respect to the transferred file; and(I) transfer the synchronization target file to the remote file server so that the transferred file managed by the remote file server matches the synchronization target file. 5. A file server according to claim 1, wherein the processor is configured to perform (A) regularly. 6. A storage system comprising: a remote file server configured to manage a remote storage device; anda local file server configured to manage a local storage device and coupled to the remote file server via a communication network,wherein the local file server is configured to:(A) transfer a file in the local storage device to the remote file server via the communication network, and the remote file server is configured to store this file in the remote storage device, thereby replicating data from this file;(B) manage, as a migration-target file, the transferred file in the local storage device;(C) not delete the migration target file from the local storage device even when the (B) is completed, and delete the migration target file from the local storage device when a certain length of time has gassed from the last access time when free capacity of the local storage device falls below a specified threshold;(K) acquire, from the remote file server, won receiving a write request with respect to a stub of the migration target file that has been deleted from the local storage device, a file managed by the remote file server which is the link destination identified from this stub;(L) store the acquired file in the local storage device; and(M) update the acquired file in accordance with the write request received in the (K); and the processor is configured to release the stub when performing the (K). 7. A non-transitory computer-readable medium encoded with a computer program that causes a local file server that is coupled to a communication network to which is connected a remote file server managing a remote storage device and that manages a local storage device, to execute the following (A) through (C): (A) transferring a file in the local storage device to the remote file server;(B) managing the transferred file as a migration target file;(C) not deleting the migration target file from the local storage device even when the (B) is completed, and deleting the migration target file from the local storage device when a certain length of time has passed from the last access time when free capacity of the local storage device falls below a specified threshold;(K) acquiring, from the remote file server, upon receiving a write request with respect to a stub of the migration target file that has been deleted from the local storage device, a file managed by the remote file server which is the link destination identified from is stub;(L) storing the acquired file in the local storage device; and(M) updating the acquired file in accordance with the write request received in the (K); andreleasing the stub when performing the (K). 8. A file storage apparatus coupled to a remote file server managing a remote storage device via a communication network, the file storage apparatus comprising: a local storage device; anda local server, the local server including: a first communication interface device which is coupled to the communication network;a second communication interface device which is coupled to a user terminal for sending an access request that is either a read request or a write request specifying a file, and which is configured to receive the access request from the user terminal; anda processor which is coupled to the first and second interface devices, wherein the local server is configured to:(A) transfer a file in the local storage device to the remote file server;(B) manage the transferred file as a migration target file; and(C) not delete the migration target file from the local storage device even when the (B) is completed, and delete the migration target file from the local storage device when a certain length of time has passed from the last access time when free capacity of the local storage device falls below a specified threshold;(K) acquire, from the remote file server, upon receiving a write request with respect to a stub of a migration target file that has been deleted from the local storage device, a file managed by the remote file server which is the link destination identified from this stub;(L) store the acquired file in the local storage device; and(M) update the acquired file in accordance with the write request received in the (K); andthe processor is configured to release the stub when performing the (K). 9. A file storage apparatus according to claim 8, wherein the communication network is the Internet, and the second communication interface device is coupled to multiple user terminals. 10. A file storage apparatus according to claim 8, wherein the processor is configured to perform (A) regularly. 11. A file server according to claim 8, wherein the processor is configured to: (H) manage the transferred file as a synchronization target file upon receiving a write request with respect to the transferred file; and(I) transfer the synchronization target file to the remote file server so that the transferred file managed by the remote file server matches the synchronization target file.