[mythtv-users] mythfilldatabase stunning my system

Greg Foster greg.foster at gmail.com
Wed Jan 24 18:06:45 UTC 2007

On 1/24/07, Mike Perkins <mikep at randomtraveller.org.uk> wrote:
> Greg Foster wrote:
> > On 1/18/07, M. Scott Doerrie <mdoerri at cs.jhu.edu> wrote:
> >> I have recently had a similar problem with mythfilldatabase and thought
> >> I'd share my solution here.  We have a large channel lineup of over 500
> >> channels -- not that we get all of them, but we like to see them in the
> >> program guide because we can order them as desired.  Though
> >> mythfilldatabase may be niced, it is not all that computationally
> >> expensive.  Rather, the updates are IO intensive, and MySQL attempts
> >> them as fast as possible.  This interferes with recording and playback,
> >> causing all manner of visual artifacts.  Sometimes the backend simply
> >> stops streaming or, less frequently, exits.  I thought that increasing
> >> the mythbackend ringbuffer would be futile since the updates take well
> >> over an hour.
> >>
> >> Since the operations are IO bound, I have installed a 4G drive for the
> >> MySQL database.  The hope was that this would reduce load on the primary
> >> drive, allowing the backend to continue streaming.  Since it is an older
> >> drive and can not communicate at the same bus speed as the primary
> >> drive, I placed it on the secondary ATA bus.  (This bus also contains
> >> the DVD-RW, but I doubt I'll be watching DVDs at 5 am when I update).
> >> This solution seems to be working fine.  The frontend will rarely have a
> >> playback artifact, but they are not present in the recordings.
> >>
> > [snip]
> >
> > Scott,
> >
> > Any luck with your changes ?  Seeing the same issues here with a large
> > lineup, to the point where mythweb doesn't come back with the tv
> > listings before things time out or get ugly.
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> >
> Possible tangential solution, maybe - move your MySQL database to a
> different box? Doesn't have to be in the same box as your busy backends.

Yup.. was just thinking along those lines.  Stumbled across something
else... mythweb on my frontend only box responds in a reasonable
amount of time.  I'm starting to suspect my mythweb configuration on
the backend.  Time to dig and compare ;)


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