Magnetic disk apparatus having improved arrangement of head disk assemblies

A magnetic disk apparatus comprising:

• a housing having a front side, a rear side, a top side, a bottom side and a longitudinal axis running perpendicular to and intersecting said front side and said rear side;
• a plurality of head disk units arranged in said housing in a plurality of rows including at least front and rear rows which are spaced from each other in a direction of said longitudinal axis and forming a front space between said front row of the head disk units and said front side of the housing and a rear space between said rear row of the head disk units and said rear side of the housing, each of said plurality of head disk units including a head disk assembly and a control circuit board, each of said head disk units being surrounded by a cover in each direction except two longitudinal sides of the head disk unit which are intersected in a perpendicular manner by said longitudinal axis or by a line parallel to said longitudinal axis which runs perpendicular to and intersects said front side and said rear side so as to provide a longitudinal air passage through each of said head disk units via said two longitudinal sides;
• a central air passage provided near a center of said housing in such a manner as to space adjacent front and rear rows of said head disk units, said central air passage communicating with an outer space of the housing through the bottom side of the housing;
• fans introducing air front said central air passage into said longitudinal air passage of each head disk unit so as to discharge the air to the top side of the housing through said front space or aid rear space;
• one or more power sources supplying power to said head disk units, mounted in said housing above said plurality of head disk units;
• and
• a discharge opening provided in the vicinity of the top side of the housing through which said air discharged to the top side of the housing is discharged from said housing.