You use the Amiga DOS ADDBUFFERS command to add (or remove) the configurable buffers for your drives.
ADDBUFFERS adds buffers to the list of buffers available for a drive. Although adding buffers speeds disk access, each additional buffer reduces free memory by approximately 512 bytes. The default buffer allocation is 5 for floppy drives and 30 for hard ...
Let's consider the case of floppies
Floppy drives use DMA to transfer disk data to memory, but there are 2 intermediary steps:
The trackdisk device has to read the data as raw data (with error corrections and all). One 0x1600 data track needs twice as much memory for raw data
Then it has to decode it into tracks
Then the file is extracted from the sectors ...