[mythtv-users] mythfilldatabase stunning my system

M. Scott Doerrie mdoerri at cs.jhu.edu
Thu Jan 18 16:14:41 UTC 2007

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.

Scott Doerrie

Michael T. Dean wrote:
> On 11/27/2006 01:19 PM, John Andrunas wrote:
>> I have found that running the optimize db script prior to doing 
>> mythfilldatabase dramatically improves the performance as well.  I was 
>> having a similar issue and as soon as I started running the optimize 
>> db script I never noticed it again.
> Another great reason to run optimize_mythdb.pl in a daily cron job (as 
> suggested in the comments at the top of the script).
> Mike
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