[mythtv-users] DVB-S multirec: how many recordings per card?

[Andre]

On 19 Nov 2010, at 18:15, Stefan G. Weichinger wrote:

> Am 19.11.2010 18:14, schrieb Another Sillyname:
> 
>> More importantly have a look at you target satellites and the channels
>> therein, now look at the Mux spread, you may well find that you never
>> have more then 2 channels that you want to watch on the same Mux
>> anyway.  If this is the case then there's little or no point
>> allocating more then 2 multi-recs per card tuner as they'll never be
>> able to record more then that.
> 
> Hmm, this might explain why I sometimes get conflicts for recordings
> even when I would have tuners left.
> 
> For example, wanting to record 5 things in parallel, having 2x3
> recordings set (2 cards with 3 recs each) and I get a conflict ... this
> was leading me to my question!
> 
> I was (and am) afraid to silently miss recordings if I set that value
> too high ...
> 
> So would I be safe anyway with a setting of 3 (and just get a conflict
> as mentioned)? Or should I go for "2"?

You will need 2 virtual tuners just to do recording overlaps even if there is only one channel per mux!

To give you a datapoint I find that 4 virtual tuners works well with a dual tuner slave backend that has a 1.8Ghz C2D cpu clocked at 1Ghz for quiet running and 2GB ram. I can record 4 HD streams in the tests I did and I find that 2 virtual tuners is used a lot of times for overlaps, 3 is used sometimes, 4 I've never seen "in the wild" but I know I can record two shows on two channels with overlaps.

I have 5 sata disks to spread the load but they are shared between a master and nfs slave backend, The master has a Q6600 2.4Ghz C2Dquad 4GB ram, grand total of 6 tuners, 24 virtual tuners. 

I just kept piling on more recordings until I got breakup in recordings, 4 works 5 doesn't, for me anyway. I've had 19 simultaneous recordings in tests, 11 of those HD. I used to have 2 virtual tuners per card and some failed recordings, upgrading to Ubuntu 10.04 made 2 reliable and later changing motherboard (same cpu & ram) got me to 4 per card.

You need to set everything to max (5) get a channel plan (king of sat maybe) and pile on the recordings until it breaks then back off a little :-)

Andre

> 
> Thanks! Stefan
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