Abstract: When a master name node has created a file, the master name node performs meta-information synchronization with only a slave name node, and does not perform the meta-information synchronization with a dummy name node. The master name node performs the meta-information synchronization with the dummy name node asynchronously with file creation. Furthermore, the slave name node stores the same meta-information as that stored in the master name node, and the file is stored in a data node placed in the same node as the slave name node and a data node placed in the same node as the master name node.

Abstract: A forced recording medium cartridge unloading system for use with a library apparatus which is operatively connected to a plurality of host computers. Interposed between the host computers and the library apparatus is a library controller that supervises and controls the library apparatus. The library controller issues a forced recording medium cartridge unloading command in response to a key input or to a request from any one of the host computers. An accessor of the library apparatus upon receipt of the forced unloading command from the library controller in turn issues a forced recording medium cartridge unloading command to a recording medium drive unit that writes and reads data to and from the recording medium cartridge loaded therein. This causes the recording medium drive unit forcibly to unload the recording medium cartridge left loaded inadvertently therein.

Abstract: In a mass storage system, a method for controlling the stepping feed of an information medium (T) on which recording tracks are formed by stripes (T.sub.n) which run diagonally or vertically across the information medium is disclosed. According to this method, the feed of the information medium (T) begins after the completion of the recording or reading operation of data (DATA) upon a first recording track (T.sub.n) and prior to the completion of the checking of the content of the data (DATA). After that, it is determined whether the feed of the information medium is continued or reversed should be in accordance with the result of checking the content of the data (DATA). That is, when no error is detected as a result of the checking, the feed is continued so as to perform the recording or reading operation of data (DATA') upon a second recording track (T.sub.n+1).