The Linux SCSI programming HOWTO: Driver Defaults 13. Driver Defaults13.1 Transfer LengthsCurrently (at least up to kernel version 1.1.68) input and output sizes have to be less than or equal than 4096 bytes unless the kernel has been compiled with SG_BIG_BUFF defined, if which case it is limited to SG_BIG_BUFF (e.g. 32768) bytes. These sizes include the generic header as well as the command block on input. SG_BIG_BUFF can be safely increased upto (131072 - 512). To take advantage of this, a new kernel has to be compiled and booted, of course.13.2 Timeout And Retry ValuesThe default timeout value is set to one minute (Timeout = 6000). It can be changed through an ioctl call (see section sec-ioctl). The default number of retries is one. u