Structures and methods are disclosed for verifying integrity of peer-supplied content in a peer-to-peer content distribution system, for example, to verify that content supplied from a sending peer node to a receiving peer node corresponds to the content that was requested by the receiving node. One implementation involves maintaining a scalable multi-node file system cache in a local cluster file system, and caching local file data in the cache by fetching file data on demand from a remote cluster file system into the cache over the network. As a result, a combination of the original paper size and the print paper size intended by a user can be set securely even in the above print type, so that useless print can be prevented securely. The method comprises setting a correlation between a step difference of a test pattern and an etched thickness of a main pattern, then applying the CMP to a semiconductor substrate having the test pattern and the main pattern for a predetermined time. The gate includes an upper gate plate, a plurality of recesses formed on a lower surface of the upper gate plate, and a lower gate plate facing the upper gate plate.