MULTIBUF allocates several buffers of shared memory for double buffering. The size of each buffer is the product of the blocksize and the number of blocks given in the Multibuf Options-Menu. An example: If you set the blocksize to 10240 and the number of blocks to 100, MULTIBUF will have a buffersize of bytes. If you choose 10 buffers in this menu, you will have approximately 10 Mbytes of buffers which should be a good setting for slow tape drives on mashines with enough physical memory. When not using compression, you might not need any double buffering.