nbs=value – sets a fixed
block size
nmin=value – sets the
minimum size
nmax=value – sets the
maximum size
nincr=value – sets the
increment size
uincr=var enables variable
increments between the min/max values
ndsize=value – sets the
device size
udefault is 512 bytes for disks
uobtained via IOCTL on some OS’s