Method and system of buffering data written to direct access storage devices in data processing systems

A data processing comprising:

• a plurality of host computers;
• a storage system including a plurality of direct access storage devices and a storage controller having a buffer memory, the storage controller being connected to each of the plurality of direct access storage devices by a storage path and to each of the host computers by at least a first channel;
• means responsive to receipt of data for a record over a channel for determining if the record is part of a track image in the buffer memory;
• means responsive to determination that the record is not part of a track image for determining if a format for the record is of a particular format;
• means responsive to determination that the format for the record is of a particular format for checking for allocation of space for the record in the buffer memory;
• means responsive to allocation of insufficient space for the record for allocating additional space in the buffer memory for caching or non-caching record;
• and
• means for destaging the record from the buffer memory to a direct access storage device;
• means responsive to destaging the record from the buffer memory to a direct access storage device for determining if the record is a caching record or a non-caching record;
• means, responsive to determination that the record is a non-caching record, for deallocating the space for the record in the buffer memory.