1. A method of buffering first requested data from a first file in a hierarchical data storage system including memory, a primary storage device, and a secondary storage device, the secondary storage device including a first logical data unit having a logical unit size, the method comprising: allocating data buffers in the memory including a first data buffer; receiving a first no recall data request associated with a first file-based identifier to the first requested data, if the first requested data is not stored on the primary storage device; retrieving the first requested data from the first logical data unit of the secondary storage device, responsive to the first no recall data request; selecting the first data buffer based on a relative availability status of the first data buffer; storing the first logical data unit in the first data buffer; associating the first data buffer with the first file-based identifier; and organizing the first data buffer among the data buffers based on the first file-based identifier.