hm... looks like we hit this:

static void
westerndigitalhung(Drive *d)
if((d->portm.feat&Datapi) == 0 && d->active && TK2MS(d->intick) > 5000){
dprint("%s: drive hung; resetting [%lux] ci %lx\n",
d->unit->name, d->port->task, d->port->ci);
d->state = Dreset;

is ms in TK2MS refering to milliseconds? if this is the case, the error occurs mutch
faster than 5 seconds after i started the dd. maybe my machine is not time callibrated