The data pipe buffers setting controls the amount of shared memory allocated for data pipes on each client or MediaAgent computer. By default, on each client computer, the system allocates 90 pipeline buffers, each with 64KB of memory. (90 buffers multiplied by 64KB equals approximately 9 MB of shared memory.)
You can configure additional buffers for transferring data between the client and the MediaAgent. Having more pipeline buffers may translate into faster dedicated (non-multiplexed) backups to tape devices, and therefore improve data transfer performance. Additional buffers consume more shared memory.