A parallel computer includes a plurality of processors arranged in a taurus mesh network, with each processor having a local memory, and a plurality of secondary storage units. The network is coupled to a host computer via a host interface. Interleave system information corresponding to the size of portions of a file to be divided and stored in the plurality of secondary storage units is also stored in the local memory of a processor. When the processor accesses the file, the interleave system information of the file in the processor local memory is referenced by the processor and the processor outputs a file transfer request in accordance with the interleave system information. In addition, when a file which is stored in accordance with given interleave system size information is to be accessed by another interleave system having different size information, it is recognized by a host interface that the access is by a different interleave system and the file can be stored again according to the different interleave system.