[mythtv-users] how many concurrent recordings possible? in HD?

John P Poet jppoet at gmail.com
Fri Dec 9 18:26:09 EST 2005

On 12/9/05, mrwester <mrwester at gmail.com> wrote:
> Hi-
>  My mythtv system has 1xPVR-350, 1xPVR-500 using ivtv 0.4, and a newly added
> DViCO FusionHDTV 5 Lite using DVB drivers.   1x200GB seagate+1x300GB seagate
> HD LVM with XFS for /video and 1x40GB seagate for FC4 OS. I have DMA
> enabled. DVI out via fx5200 at 1280x768.  Chaintech nforce2 mobo, AMD2900
> with 1gb ram.  All 4 tuners can capture on their own with no problems.  I
> can capture with all 3 Hauppauge tuners at the same time no problems.
> Trying to capture HDTV while capturing with the Hauppuge cards results in
> normal analog recordings but the digital recording has dropouts and
> scrambled bars across it.  I need to double check if capturing digital NTSC
> with the DViCO card also has the dropouts when one or more PVR cards are in
> use.
>  I'm new to the HDTV part of mythtv and looking for feedback to tell me if
> what I'm trying to do is realistic or not.   And if it is realistic, where
> should I look to troubleshoot.  Thanks for any insight.
>  Mike

I have four HD-3000 cards writing to a 5 disk software RAID5 formatted
as XFS.  I can record on all four cards simultaneously without any
problem.  I do *not* use LVM -- which I believe adds some overhead. 
Software raid5 on a 3GHz Pentium 4 system results in very good disk

As a test, I tried turning OFF hyperthreading on my 3.0GHz P4, and
started having problems recording more than two HD programs at a time.
 Don't know how Athlons perform, but HT is a win for Pentiums.

Another datapoint - My raid5 had to rebuild one of the disks.  During
this rebuild, I could still record one HD stream without a problem,
but two resulted in a LOT of corruption, and a lot of messages about
it taking a LONG time to get data from the HD tuner card.

I noticed that Daniel add a ringbuffer into myth's DVB processing
today, so that should help any system which is marginal.

Don't know if any of this helps you, but thought it might...


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