A dynamic block transfer size adjustment mechanism independently defines block transfer size for each memory portion, which may include files in a file system, virtual storage segments in a memory system, or extents in physical storage. By specifying block transfer size for a memory portion independently from other memory portions, the performance of the computer system may be enhanced. In addition, the block transfer size of one or more memory portions may be dynamically adjusted according to how the memory portion is used. In an alternative embodiment, the block transfer size may also be specified for each process that accesses a portion of memory. Thus, a single file may be accessed with a first block transfer size by a first process, and may be accessed with a second (different) block transfer size by a second process. By providing the ability to independently set block transfer size for portions of memory, and to dynamically adjust those values according to the historical use of the portion of memory, the performance of a computer system is enhanced.