I have my safety sausage (or as I call it DSMB) stored in my drysuit leg pocket. The DSMB is connected to the reel and is ready to go when I need to deploy it. I've tried having it all bungied together and clipped on to a D-Ring on my BCD but TBH I've found that more trouble than this worth - unlike with a harness set up I can't move the d-rings and they are all in really stupid positions.
As a general context question, I'm continually amazed to hear about people who don't have a DSMB as part of their general diving kit. Also as a boat handler, unless I'm diving in a shipping channel (at which point you are talking about mandatory return to shot, with a deco trapeze if the there is a strong current) I'd much rather each buddy pair releases a DSMB and ascends on that. I've got a clear point of reference in the water for each pair, and can count off each pair as safely left the wreck. In fact a lot of the commercial skippers in the UK make it mandatory to use a DSMB.
As for the person who said about having a mechanism where you crack a bottle and it deploys straight from your BCD, having been on a dive and had to let go of my reel because it has jammed when deploying the DSMB I'd never use such a piece of kit. Too much of a risk of an uncontrolled ascent. (To answer the obvious question, its easy to tell if a DSMB on the surface isn't connected by a line to divers. It drifts a lot quicker, or alternatively if it is snagged stays still. Worst case you pootle over and give it a quick tug at which point its obvious that someone isn't holding on to it. Goes without saying that you let them know that a single tug on the line isn't anything to be concerned about though..