[mythtv-users] Are there any throttling features in Mythtv?

[David Brodbeck]

Mike Perkins wrote:
> Sunday evening, we sat down to watch a film I'd recorded just before 
> Christmas, 2 hours long. This was about 7:45 pm. An hour and a half 
> later, the whole system hung. There was not the slightest sign that 
> anything was wrong up to the point it froze.
> 
> After some investigation of the front end[1] I discovered that the back 
> end had hung. This was because at 8:55 pm the back end had begun three 
> simultaneous recordings on three DVB-T tuners. Apparently my back end 
> couldn't cope with reading and writing four streams simultaneously[2].

Odd that it would hang instead of stuttering.  Are you sure this is an 
I/O problem, and not an overheating, memory, or power supply issue? 
Have you tried duplicating the hang to make sure it wasn't just 
coincidence?  Usually running out of disk I/O bandwidth won't hang a 
whole system -- if it did just doing a file copy would be enough to kill it.

> Now, before you all scream "throw more hardware at it!" I would like to 
> point out that whatever system you've got, a point will come when you 
> are likely to stress it. So it occurred to me to wonder if there was any 
> kind of throttling or warning available in mythtv, apart from "max # of 
> jobs to run on this backend".

I'm not sure I see the point of installing hardware and then telling 
Myth not to use it.  Wouldn't it make more sense to just not install 
more tuners than the system can handle?