To actualize plural access competition and to speed up processing by updating a bit map area exclusively for every remote adapters after track data of a temporary storage means competing against the plural remote adapters are updated when writing instructions from the plural remote adapters onto the constant bit map area compete.

This unit is provided with more than two remote adapters 1608 and equipped with a temporary storage means consisting of a track data area and a bit map area in which a one-time access unit is limited to fixed bytes and is sectioned for every cylinders of a file device and composed of a bit column indicating whether or not each section is updated. When writing instructions from the plural remote adapters 1608 onto the constant certain bit map area compete, a resource managing means 1605 makes the plural remote adapters 1608 update the track data of the temporary storage means first and then, update the bit map areas exclusively for every remote adapters 1608.