[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
throughput.

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...

John


More information about the mythtv-users mailing list